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Aristotelianism, alchemy and corpuscularianism in the thirteenth century: the problem of substantial form and its corpuscular solution

Published online by Cambridge University Press:  15 August 2025

Athanasios Rinotas Open the ORCID record for Athanasios Rinotas [Opens in a new window]
Athanasios Rinotas*
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IMT School for Advanced Studies Lucca, Lucca, Italy
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Abstract

The Avicennan text De congelatione et conglutinatione lapidum had a great influence on the alchemical thought of the thirteenth century. This Latin text disputed both the veracity of alchemy and the possibility of alchemical transmutation by arguing that art is inferior to nature and that the alchemists cannot manipulate a metal because its true characteristics are hidden from our senses; thus an alchemist cannot change something which is unknown to him. Newman’s pioneer studies examined the diffusion and impact of the first Avicennan argument on medieval alchemy and he shed light on the art-versus-nature debate. This paper has a twofold aim: on the one hand it aims to further Newman’s study by focusing on the second Avicennan argument, which is closely related to the problem of substantial form, and on the other hand it aims to show how the aforesaid problem paved the way for the emergence of corpuscularianism, which flourished during the early modern period. In this regard, it will become clear that the historiographical case of alchemy and its problem of substantial form can serve as an exegetical tool for ‘bridging’ the Middle Ages and the early modern period with respect to the relation between Aristotelianism and corpuscularianism.

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The British Journal for the History of Science , First View , pp. 1 - 17
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The connection between medieval alchemy and medieval philosophy has been acknowledged since the beginning of the twentieth century. In particular, Maurice De Wulf in his Histoire de la philosophie médiévale planted some early seeds by talking about a philosophie nouvelle which was initiated by adherents of medicine based on the observations and data collected from such disciplines as magic, astrology and alchemy.Footnote 1 Likewise, in the mid-twentieth century, another eminent scholar of medieval philosophy – Fernand van Steenberghen – referred to alchemy in his book about the philosophy of the thirteenth century, while some decades later Crisciani and Gagnon wrote a book on the relation between alchemy and philosophy in the medieval age.Footnote 2 Nowadays, modern scholars who deal with medieval philosophy seem to have reached a point of maturity on the aforementioned relation according to which medieval alchemy is recognized as a field which has received influences from and has close ties with medieval philosophy.Footnote 3

The dominant position of Aristotelian philosophy during the medieval age has meant that the relation between medieval alchemy and medieval philosophy has largely been understood as developing out of an Aristotelian model of philosophy. The main contributing factor for this developmental relationship goes back to the translation of the various Arabic texts associated with philosophy, mathematics, astrology, medicine and so on into Latin during the twelfth century. During this period a great number of Aristotelian texts were also translated from Arabic into Latin and consequently the Latin scholars became acquainted with previously unknown books by Aristotle on natural philosophy.Footnote 4 However, as many scholars have already noted, medieval Aristotelianism was not the ‘pure version’ of the term ‘Aristotelianism’ as we know it today. In fact, there were many medieval texts connected to Neoplatonism and the occult arts (magic, astrology and alchemy) which altogether were falsely circulated under the name of Aristotle.Footnote 5 As a result, medieval scholars received a version of Aristotelianism which, on the one hand, was not – strictly speaking – purely philosophical and, on the other, left much space for integration with other fields of knowledge.

In this regard, medieval alchemy availed itself of the aforementioned version of medieval Aristotelianism and thus created ties especially with the Aristotelian works on natural philosophy. As far as concerns these ties, modern scholars have particularly focused on two topics: (1) Aristotle’s theory of the formation of metals and its influence on the sulphur–mercury theory and (2) the relation between art and nature in Aristotle’s Physics.Footnote 6 These topics have been thoroughly studied by modern scholarship and have been used as loci classici in order to identify the ways in which medieval alchemy has benefited from Aristotelianism.Footnote 7

A few decades ago, William Newman published two groundbreaking studies which were related to Aristotle.Footnote 8 In particular, Newman covered a famous medieval alchemical debate which was triggered by Avicenna’s De congelatione et conglutinatione lapidum, which in turn contained two arguments against alchemical transmutation. As Avicenna has stated, an alchemical transmutation cannot happen because nature is superior to art and therefore one metal cannot be transmuted to another by means of alchemy. Furthermore, since the true characteristics of metals are hidden from human senses, the alchemists cannot manipulate what they cannot understand. The first Avicennan argument has been extensively studied by Newman, who has cogently shown that it has its roots in the second book of Physics. There, Aristotle states that art can either imitate or ‘perfect’/complete nature. As Newman noticed, Aristotle differentiated between the imitative and the perfective arts. It is in this way that the latter category of art was adopted by some medieval alchemists in order to argue that the alchemical products were not inferior to the natural ones.Footnote 9

This study has a twofold aim. On the one hand, it seeks to continue and to complement Newman’s study by shedding light on Avicenna’s second argument mentioned above, and thus to offer a more complete assessment regarding the impact of the De congelatione on medieval alchemy. On the other, it aims to challenge the trend which connects Aristotle and medieval alchemy in a positive way. In this regard, I will show that Avicenna’s second argument is associated with the Aristotelian notion of substantial form, which posed in turn great difficulties to medieval scholars in explaining and accepting the possibility of alchemical transmutation.Footnote 10 As a result, it will become evident that Aristotelianism could also be deemed a decisive factor in putting alchemical transmutation into serious question during the thirteenth century. Additionally, it will be shown that the problem of substantial form was a crucial factor and paved the way for the emergence of corpuscularianism, which flourished during the early modern period. In Robert’s accounts of medieval atomism it is cogently argued that the thirteenth century was not characterized by any strong presence of atomic and corpuscular theories.Footnote 11 This study offers a partial explanation of this direction: namely that the thirteenth century could be interpreted as an ‘incubation stage’ for the emergence of both later medieval and early modern atomic and corpuscular theories, since the problem of substantial form led medieval scholars and alchemists to explore new avenues for explaining the phenomenon of alchemical transmutation. In this way, atomism and corpuscularianism served as a plausible solution to the aforesaid problem. In supporting my claims, my argument will be set forth through the following steps: in the first part of my paper, I will provide a brief introduction to Newman’s study of the De congelatione and how Avicenna’s second argument is related to Aristotelianism. In the second part, I will show which medieval scholars dealt with Avicenna’s second argument and what was their attitude towards the problem of substantial form. In the final part, I will examine the reaction of medieval alchemists to the Avicennan challenge and will argue for the emergence of corpuscularianism through the text of Summa perfectionis. As a final note, through the last step, it will become apparent that the problem of substantial form acted as a ‘bridge’ between the Middle Ages and the early modern period with respect to the emergence of atomism and corpuscular theories.

Avicenna’s second argument in De congelatione and its connection to Aristotelianism

During the twelfth and thirteenth centuries a great number of alchemical texts were translated from Arabic into Latin.Footnote 12 One of these texts is Avicenna’s De congelatione, which was translated by Alfred of Sareshel around 1200 and was added to Aristotle’s Meteorologica. The story of the translation of the De congelatione runs as follows. Earlier in the twelfth century, Gerard of Cremona had translated the first three books of Aristotle’s Metereologica, while the fourth book was translated in 1156 by Henricus Aristippus. Alfred added his translation of the De congelatione to a manuscript which already contained the translations of Gerard and Aristippus and thus the Avicennan text was passed as an Aristotelian one.Footnote 13 Yet, as Mandosio and Di Martino have shown, Alfred was well aware of the fact that the De congelatione was a text actually written by Avicenna and yet he still chose to add it to Aristotle’s Meteorologica on the ground that Avicenna was the ‘best imitator’ of Aristotle and he was thus filling in the gap left by Aristotle in the Meteorologica.Footnote 14 Under the name of Aristotle, the Avicennan text enjoyed great fame and it occupied the minds of great medieval scholars. The first to recognize the true identity of the Avicennan text was Albert the Great, who, in his commentary on Peter Lombard’s Sententiae – written between 1248 and 1249 – clearly attributes the text to Avicenna.Footnote 15

The main position of the De congelatione is summarized through the Latin short text: ‘sciant artifices alkimie species metallorum permutari non posse’ (‘let the artisans of alchemy know that the species of metals cannot be transmuted’), according to which the transmutation of metals is not possible.Footnote 16 Yet this seemingly Avicennan attack on alchemy, which is expressed in the Sciant artifices (the previous short text is often referred to through its starting words), is ‘alleviated’ further in the text by recognizing that a transmutation is possible if the metal is first reduced to its prime matter.Footnote 17 As I mentioned in the introduction, Avicenna rejected alchemical transmutation by employing two arguments which are found in turn in the following excerpt of the De congelatione:

Art is weaker than nature and does not overtake it, however much it labors. Therefore, let the artificers of alchemy know that the species of metals cannot be truly transmuted. But they can make similar things and tint a red [metal] with yellow so that it seems gold, and tint a white one with the color that they want until it is very similar to gold or copper. They can also cleanse the impurities of lead, although it will always be lead. Even though it may seem silver, alien qualities will dominate in it, so that men err in this just as those who accept [artificial] salt and sal ammoniac err. I do not believe that it is possible to take away the specific difference by some technique because it is not due to such [accidents] that one complexion is converted into another, since these sensible things are not those by which species are transmuted; rather they are accidents and properties. For the differences of the metals are not known, and since the difference is not known, how will it be possible to know whether it is removed or not, or how it could be removed?Footnote 18

At the beginning of this excerpt, we find Avicenna’s first argument according to which art is inferior to nature and thus cannot accomplish what nature does. In this regard, since alchemy is an art, its products cannot be equal to those of nature and therefore metals which are produced by means of alchemical transmutation are not genuinely the same as the natural ones.Footnote 19 A bit further on in the text, Avicenna deploys his second argument, which is our main interest. According to this argument, the accidents of a metal are not responsible in any way for converting metals and in general ‘these sensible things’ are not capable of bringing about a transmutation. In fact, the true differences of metals are not known and they are hidden from our senses and therefore the alchemists cannot manipulate what they actually cannot understand. In order to understand Avicenna’s argument, we need to provide some context. As Newman has already pointed out, Avicenna’s second argument subscribes to Aristotle’s theory of mixture and the imposing of a new substantial form.Footnote 20 In Aristotle, the qualities of elements (cold, hot, dry, wet) are responsible for bringing about transmutation or elemental change. Yet Avicenna had opposed this doctrine. For Avicenna, the elemental qualities could not be responsible for bringing about a new substantial form because then this theory would commit itself to circular causation. In principle, substantial forms cannot be identified with their qualities because then they would be ontologically both posterior and prior to themselves, which is impossible.Footnote 21 Given this impasse, Avicenna postulated that substantial forms are hidden from our senses and they are bestowed on things by an external immaterial entity, the Giver of Forms.Footnote 22 Turning to Avicenna’s argument now, it becomes clear why accidents cannot be responsible for a transmutation, since accidents – that is, qualities – cannot be responsible for bringing about a new substantial form to metals. The latter proposition would have evoked Avicenna’s objection of circular causation. Then, Avicenna concludes, the true characteristics of metals – that is, their substantial forms – are hidden from our senses and thus alchemists cannot remove what they do not actually know.

Assessing the above, it becomes obvious that substantial form was a decisive factor for determining the existence of a thing, and likewise, according to Avicenna’s argument, a true and genuine alchemical transmutation would entail a substantial change, not at the superficial level of accidents/qualities of a metal, but rather at the depth of it, where substantial form was supposed to be lurking. Pasnau has noticed that Avicenna was the initiator of a version of substantial form in the scholastic tradition, according to which ‘the substantial form can be viewed as playing something very much like the role of an internal efficient cause, sustaining and regulating the existence of that which the efficient cause originally produced’.Footnote 23 In this regard, Avicenna’s doctrine of substantial form posed an actual difficulty in alchemical theory. As we will see, the problem of substantial form can be detected in various medieval authors who dealt with alchemy.

The problem of the substantial form in the alchemy of the thirteenth century

In this section I will show how Avicenna’s second argument can be traced in alchemical treatises and books of the thirteenth century. I will try to preserve the relevant chronological order of the medieval texts and authors in order to show how the problem of substantial form was presented and treated throughout the aforementioned century.

Our first case study is Albert the Great (1200–80) and his De mineralibus, which was written between 1254 and 1257.Footnote 24 By writing this book, Albert aimed at filling the gap that Aristotle left in his Meteorologica, and thus the Dominican master produced an account of metals and stones which was Aristotelian in character. It is also this book that contains Albert’s most references to alchemy.Footnote 25 As has already been mentioned, Albert knew the Sciant artifices; indeed, it exerted a great influence on his work from a very early point in his intellectual career.Footnote 26 Albert made use of the Avicennan dictum in order to express his openness to the possibility of alchemical transmutation, and in the ninth chapter of the third book of the De mineralibus he describes the operation of the alchemists as follows:

But then we must say that skillful alchemists proceed as skillful physicians do: for skillful physicians, by means of cleansing remedies clear out the corrupt or easily corruptible matter that is preventing good health … And we shall say that skillful alchemists proceed in entirely the same way in transmuting metals. For first, they cleanse thoroughly the material of quicksilver and sulphur, which, as we shall see, are present in metals. And when it is clean, they strengthen the elemental and celestial powers in the material, according to the proportions of the mixture in the metal that they intend to produce. And then nature itself performs the work, and not art, except as the instrument, aiding and hastening the process, as we have said. And so they appear to produce and make real gold and real silver.Footnote 27

In this excerpt Albert draws clear connections between alchemy and medicine with respect to their operation, while the Dominican master purports that the alchemical operation is carried out by nature and not art. Despite this favourable position of Albert towards alchemy, there are excerpts in the same book which show that Albert was also concerned about the problem of substantial form in the alchemical transmutation. As we saw earlier, Pasnau has noticed that Avicenna initiated a version of substantial form which was adopted by various scholars of the Middle Ages. One of these scholars was Albert, who clearly conceives of substantial form as an internal efficient cause which sustains and regulates the existence of metals.Footnote 28 This becomes evident in the seventh chapter of the third book of the De mineralibus, where Albert states,

For there is no reason why the material in any natural thing should be stable in nature, if it were not perfected by a substantial form. But we see that silver is stable, and tin, and likewise other metals; and therefore they seem to be perfected by substantial forms.Footnote 29

This small passage argues that the stability of a metal is strictly bounded by its substantial form and thus the latter acts as an internal efficient cause which sustains and regulates the existence of the metal. But what about the Avicennan tenet that the substantial form is hidden from the senses and therefore unknown? Albert seems to be aware of the latter Avicennan position as he provides a definition or description of homeomerous bodies. Albert’s account runs as follows: ‘For a homeomerous substance has the same specific form, inside and outside, occult and manifest, in the depths and on the surface. And it is established that metals are included in the [group] of homeomerous things.’Footnote 30

Before we proceed with the analysis of the passage, it should be mentioned that the terms ‘specific form’ and ‘substantial form’ were used interchangeably during the Middle Ages.Footnote 31 In this regard, Albert describes what happens with the substantial form of a metal and he alludes to Avicenna’s doctrine. For Albert, a metal, as homeomerous, should have the same substantial form ‘intus et extra et in occulto et in aperto et in profundo et in superficie’ (‘inside and outside, occult and manifest, in the depths and on the surface’). He thus evokes Avicenna’s claim according to which a genuine substantial form should not only be in the exterior parts of a metal but also and most importantly in the interior ones. The existence of the substantial form in the internal parts of a metal is the ultimate criterion for Albert for determining its true identity and genuineness. This is clearly stated when Albert refers to the unsuccessful efforts of the alchemists to bring about a genuine alchemical transmutation by means of elixir. Again in Chapter 8 of Book Three the Dominican master says,

Besides, we have rarely or never found an alchemist, as we have said, who [could] perform the whole [process]. Instead, by means of the yellow elixir he produces the color of gold, and by means of the white elixir, a color similar to silver, attempting to make the color remain fast in the fire and penetrate throughout the whole metal, just as a spiritual substance is put into the material of a medicine. And by this sort of operation a yellow color can be induced, leaving the substance of the metal unchanged.Footnote 32

In this source Albert notices that there is hardly any alchemist who has performed the alchemical process successfully; instead the only thing they do is superficially colour the metals without affecting their substance. In this way the depth or internal part of a metal is left unaffected and therefore no genuine transformation has been performed. Albert goes a step further in the next chapter when he says, ‘But those who color [metals] white with white, or yellow with yellow [colouring], leaving the specific form of the original metal unchanged in material – without doubt they are deceivers, and do not make real gold and real silver.’Footnote 33

In this passage, Albert becomes more precise and affirms that it is due to the endurance of the previous specific form (that is, substantial form) of a metal that one may determine the success of alchemical transmutation. The alchemists who have failed to change the already existing substantial form are deceivers and not capable of producing genuine metals. The last two excerpts allude to Avicenna’s second argument since alchemists, according to Albert, seem to be ignorant of the true characteristics of metals, and this is proved by the fact that they cannot affect and change the substantial form.

Another text which was contemporaneous with that of Albert the Great was the Liber secretorum alchimiae. This text was written in the northern parts of Italy in 1257 by Constantine of Pisa, who was a student of medicine.Footnote 34 Therefore the text consists of lecture notes and it draws a close connection between alchemy and medicine. Yet the book’s great significance and importance lie in the fact that it proves that alchemical topics were at least discussed within the realms of medieval universities. This should not come as a surprise since alchemy is also attested as a topic within the introductory university compendia of the University of Paris.Footnote 35 As Barbara Obrist has already noted, the Liber secretorum alchimiae is influenced by three main intellectual backgrounds; that is, Aristotle’s natural philosophy, Plato’s cosmological ideas deriving from the school of Chartres and the Bible.Footnote 36 This is not the place to deal with these influences extensively since our focus will be on the Sciant artifices and its appearance in Constantine’s book.

Constantine was well aware of the Avicennan dictum and his quotes seem to evoke and allude to Avicenna’s second argument from the De congelatione. As a matter of fact, Constantine’s use of the Sciant artifices is close to Albert the Great’s previous statements, according to which a more profound transmutation was needed in order to determine a true and genuine substantial change in a metal. In the first chapters of the Liber secretorum Constantine speaks about a mixtum coming from copper and tin whose final product has profit as a goal and not true appearance and existence. In this regard, Constantine refers to the Sciant artifices by saying,

because as Aristotle says at the end of the fourth book of the Meteorologica: ‘Let the alchemists know’, and the like, where he speaks about the sophists, because sophists make operations for the purpose of tingeing bodies and not for the purpose of lastingness or depth, because where there is depth [profundatio] there is also lastingness [perpetuatio] but where there is no depth, there is no lastingness either; and for that reason there is only appearance there but not existence.Footnote 37

Contrary to Albert, Constantine is not aware of the true identity of the author of the Sciant artifices and he attributes it to Aristotle. Quite interestingly, Constantine associates the Avicennan dictum with sophistry and non-genuine transmutation. As Calvet informs us, this kind of association stems from the De sophisticis elenchis where Aristotle explains sophism by using the example of genuine gold which is to be distinguished from the tinged one, which in turn has the appearance of gold according to the senses.Footnote 38 This remark already creates allusions to the second argument of Avicenna’s De congelatione since Aristotle’s reference to the senses indicates that the true characteristics of genuine gold are hidden from the senses. However, Constantine initiates two terms – perpetuatio and profundatio – which both clearly indicate the problem of substantial form and substantial change. In particular, for Constantine the actual existence of a metal is connected with its depth (something also seen in Albert), meaning that a homeomerous body should be the same in its depth and its surface. In this way, a metal will have lastingness too, meaning that its substantial form should be perdurable and not synonymous with its accidents and qualities which reside at the surface of the metal.

Constantine becomes more precise on the subject of ingenuine transmutation at the beginning of the ninth chapter, where he says,

We proceed now to transformation by sophistry, of which Aristotle also speaks at the end of the fourth [book] of the Meteorologica concerning what ‘Alchemists know’ and so on. For he himself speaks of changing and coloring of bodies, but not of their change in depth or their being made perdurable. To that purpose he says: ‘They do extraneous things to deceive people.’ And again: ‘Nor do I believe that one body can be changed into another unless it be brought back to primary matter which is mercury … There are some who achieve the appearance but not existence, and all of which is sophistical.’Footnote 39

In this excerpt Constantine becomes more explicit, clarifying that the Sciant artifices denotes a transmutation by sophistry which is concerned with coloration of bodies alone and not their change in depth or their being made perdurable. Once again Constantine employs the terms profundatio and perpetuatio in order to argue that only the appearance of metals is affected and not their existence since their substantial form is left unaffected. With respect to profundatio Constantine becomes more detailed in the twelfth chapter, where he states,

We continue now to fundamental change. Profundatio as its etymology indicates is prorsus fundatio, that is fundamental change, with the parts separated and changed into something which did not exist before, and thus bringing about permanent change, since no lastingness can be effected without previous fundamental change. Now fundamental change is the removal of sophistry, for every action is futile and every alchemical operation useless unless the body be reduced by founding.Footnote 40

In this source, Obrist has chosen to translate profundatio as ‘fundamental change’, connoting in turn the term of substantial change. The whole context of the excerpt suggests this interpretation since fundamental change involves a procedure according to which the parts should get separated and then changed into something which did not exist before. In this regard, a new substantial form should be bestowed on the metal in order for a genuine transmutation to take place, and not a sophistry. Constantine, like Albert, poses the problem of substantial form and substantial change as a key factor for determining a true transmutation, while the true characteristics of a metal are hidden from our senses and thus profundatio is the key for bringing about a permanent change.

Our next case will be concerned with Thomas Aquinas and his approach towards alchemy. Assessing Thomas Aquinas’s opinion on alchemy is a difficult task because he did not have a uniform attitude towards the hermetic art during his intellectual career. In fact, the aforementioned assessment becomes even more difficult if one takes into account the alchemical pseudo-epigraphic works that circulated under the name of the Angelic doctor.Footnote 41 For instance, in the Expositio super librum Boethii de Trinitate, which was written in 1256, Thomas notes that the alchemical vessels and equipment fail to regenerate the proper conditions that exist in the bowels of earth and, therefore, art cannot imitate nature. In this regard, alchemy is classified as a mechanical art like medicine and agriculture.Footnote 42 In his commentary on the Meteorologica, Thomas presents a more favourable position towards alchemy but this shift in his writing can be explained by the fact that this work was left unfinished by the Dominican master. This positive attitude towards alchemy is thus most probably the addition of an anonymous writer.Footnote 43

Be that as it may, my focus here will be on a source that has been already treated by W. Newman, only that his stress in the analysis of the source was put on the inferiority of art. Yet, as I will show shortly, the very same source has a further relation to Avicenna’s second argument and the problem of the substantial form. This source is concerned with Thomas Aquinas’s commentary on Peter Lombard’s Sententiae, written between 1252 and 1256. There Thomas deals with the question whether demons can induce a true corporeal effect in corporeal matter and in his fifth response contra he rejects this possibility by employing the Sciant artifices:

Moreover, demons do not work except by the method of art. But art cannot give a substantial form, whence it is said in the chapter on minerals: ‘the artificers of alchemy should know that species cannot be transmuted.’ Therefore, neither can demons induce substantial forms.Footnote 44

The crucial point in this source is that Thomas rejects a demon’s capacity to induce corporeal effect on corporeal matter on the ground that art cannot bring about a substantial form, and in support of this contention he evokes the Sciant artifices. In this regard, he alludes to Avicenna’s second argument, since art does not have the power to effect the depth of a thing and bring about a true substantial change. In addition, Thomas seems to stick to his general position about art and artefacts according to which art can only bestow an artificial form on an artefact and not a substantial one.Footnote 45 Yet what we should keep in mind is that the problem of substantial form is also stressed by Thomas. The Angelic doctor becomes more explicit in the final settlement of the question, where he says,

Art by its own power cannot confer a substantial form, but it can do this by means of a natural agent, as is clear in the following – that the form of fire is produced in logs through art. There are some substantial forms, however, that art cannot induce by any means, since it cannot find the proper active and passive subjects. Even in these, art can produce a similitude, as when alchemists produce something similar to gold as to exterior accidents. But it is still not true gold, since the substantial form of gold is not [induced] by the heat of fire – which alchemists use – but by the heat of the sun in a determinate place where the mineral power flourishes. Hence such [alchemical] gold does not operate according to the specific form [of real gold], and the same is true for the other things that they [i.e., alchemists] make.Footnote 46

As I have already mentioned, Newman has examined this source twice. In both instances he mainly focused on the last parts of the excerpt. According to Newman, Thomas rejects alchemy on the grounds of virtus loci. Particularly,

his idea is that metals can be generated only by natural heat operating in the subterranean chambers where ores and metals come into being. It is a priori impossible for man to make metals artificially, since he cannot erect his laboratories in the hidden subterranean depths where the ‘mineralizing power’ operates with the aid of solar heat.Footnote 47

Yet Newman’s commentary has left room for further interpretation, since the first part of the excerpt is not properly discussed.

While, at the beginning of the source, Thomas once again reiterates that art cannot bring about a substantial form, thereafter his position becomes more nuanced, since he accepts that there can be exceptions if art will make use of natural agents. Yet Thomas returns quickly to his initial position by admitting that there are substantial forms that cannot be induced in any way because art cannot ‘find the proper active and passive subjects’. But what exactly does Thomas mean here? First of all, it should be mentioned that this small phrase alludes to Avicenna’s second argument, since it implies that the actual characteristics of a metal are hidden. Newman’s translation is here open to revision, since the verb invenire can also mean ‘contrive’, while the term propria should be left as it is because it is a key Thomistic term. According to Shields and Pasnau propria are accidents that are not part of a thing’s essence but are the necessary consequences of that essence and because propria are necessarily connected with the essence, we can use the propria to signify the essence.Footnote 48 Likewise De Boer notes that these accidentia propria, even though they do not belong to the essence, still are not separable from it. These propria, rather, ‘flow forth’ from essence.Footnote 49 As Weigel puts it, they emanate from the essence but they are not part of it.Footnote 50

So, in light of this, the source can be interpreted as follows: some substantial forms cannot be induced in any way because art cannot contrive the proper accidents which are necessarily connected to the essence of the metal. In simple words, the true characteristics of metals (propria) which signify their true being (essence) are unknown to us and therefore art cannot bestow a new substantial form on metals. As a final note, it should be remembered that in Aquinas’s philosophy essence is connected to substantial form even though they are not the same thing.Footnote 51 According to Aquinas the essence of a material thing is its substantial form with its matter and thus propria become integral in a substantial change.Footnote 52 Since propria are either unknown or hidden, it is impossible for them to be contrived and therefore the alchemists are only able to produce similitudes which are devoid of a true substantial form.

The problem of substantial form is also met in another text of the thirteenth century which was falsely attributed to Venerable Bede. The text, called Sententiae, sive axiomata philosophica ex Aristotele et aliis praestantibus collecta, una cum brevibus quibusdam explicationibus ac limitationibus, is highly Aristotelian in its content and it contains many philosophical topics ascribed to Aristotle. In its treatment of the Sciant artifices it seems to have been influenced by Aquinas as it runs as follows:

The alchemists say that by means of their art gold can be produced from iron or copper. By which it is said that gold or silver is produced by iron or copper in terms of appearance but still not in terms of existence. And the reason [for that] is that by means of no art can a substantial form be placed in the specific being of another form.Footnote 53

In this excerpt, even though Pseudo-Bede does not mention the Sciant artifices, he makes clear allusions to it. According to him alchemists are able to convert metals only apparenter (in terms of appearance) and not existenter (in terms of existence) because art is incapable of inducing a substantial form for a metal. Pseudo-Bede stresses once again the problem of substantial form in a variegated way by saying that a substantial form cannot be placed in the specific being of another form. He thus implies the Aristotelian tenet of the fixity of the species.

Our last case study is Giles of Rome, who was also influenced by Thomas Aquinas. Giles has not dealt extensively with the topic of alchemy and his most detailed treatment of it exists in his Quodlibeta, a work which is primarily concerned with religious matters. In this work Giles poses the question whether man can make gold by art, and in his contra response he uses the Sciant artifices in order to deny such possibility.Footnote 54 In this instance, Giles evokes the Avicennan dictum without any reference to substantial form: this reference, however, happens further on, where Giles affirms that a natural generation of perfect metals is not possible. According to Giles, a transmutation in terms of colour and accidents may occur, but not in terms of substantial form because then the virtus loci would have been required for a successful generation of metals.Footnote 55 Without doubt, Giles seems to follow the lead of Thomas Aquinas regarding his approach towards alchemy. Yet the important thing is that he is well aware of the Sciant artifices and, evidently, he employs once again the notion of substantial form in order to show that such a transmutation is not possible due to the lack of the mineralizing power that exists in the bowels of earth.

Thus far, we have seen that Avicenna’s second argument in the De congelatione is associated with the problem of substantial form, which has been traced in turn, in various medieval authors. However, despite the difficulties that the substantial form posed, it also triggered a reaction aimed at surmounting this problematic obstacle. This ‘reaction’ will be the topic of our next examination.

The reaction to the problem of substantial form

The Sciant artifices and the problem of substantial form triggered a reaction during the last quarter of the thirteenth century, the occurrence of which, in retrospect, seems natural and expedient. From the sources and authors that have been examined, it is evident that alchemists were often accused of sophistic transmutation; that is, a transmutation that was able to affect the surface of a metal without altering its depth and true characteristics. In this regard, at the end of the thirteenth century, medieval alchemy and its adherents were under increasing pressure for a more micro-level explanatory approach to alchemy’s procedures, in particular that of transmutation.

Evidence of this shift can already be traced in the late works of Thomas Aquinas, who, in his Summa theologica, written in 1272, deploys a more favourable position towards alchemy, saying,

If, however, real gold were made by alchemy, it would not be illicit to sell it as true gold, because nothing prohibits art from using any natural causes for the purpose of producing natural and true effects; as Augustine says in De trinitate Book III, of those things which by the art of demons are made.Footnote 56

The shift towards a micro-level explanation of alchemy is not directly apparent in this source. Thomas Aquinas affirms that it is licit to sell alchemical gold as true because art can use natural causes in order to produce natural and true effects. Thomas then quotes St Augustine in support of his position. As Tarrant has recently shown, Thomas evokes Augustine’s doctrine of ‘seeds’ or seminal reasons; that is, a kind of particle that resides within the corporeal elements and could be utilized for bringing about certain effects. According to Augustine, these seeds were invisible to the human eye but still humans could see them by exercising their reason.Footnote 57 Thomas’s invocation of the Augustinian seeds implies a shift towards a micro-level explanation of alchemy, which could explain in turn what might happen at the depth of a metal if one aims at accomplishing a true metallic transmutation.

Yet the greatest micro-level shift that has been noted is the association of medieval alchemy with corpuscularianism. As Pasnau has already meticulously argued, it was the problem of the substantial form that allowed the emergence of corpuscularianism in the high Middle Ages. As Pasnau eloquently stresses,

As the scholastic era advances, the physical aspect of substantial form becomes increasingly dominant: substantial forms explain a substance’s unity and persistence, but they do so by playing a specific causal role within a substance, rather than by serving as an abstract metaphysical principle. The consequence of this approach is to open the door to corpuscularianism. For when substantial forms are so understood, the theory stands or falls with the alleged failure of any reductive account of the alleged causal role. If the physical phenomena associated with persistence and unity can be explained mechanistically, substantial forms become unnecessary.Footnote 58

In this regard, it is the Summa perfectionis of Pseudo-Geber that best captures and delineates alchemy’s shift towards a micro-level explanatory scheme; that is, corpuscularianism. However, the most impressive thing in Pseudo-Geber’s corpuscular alchemy is that it was also based on Aristotelianism. In what remains I will present a brief exposé of the Summa which shows on the one hand its corpuscular character and, on the other, its Aristotelian influence.Footnote 59

The Summa perfectionis was written at the very end of the thirteenth century and was attributed to Geber, a Latin transliteration of the name of Jabir Ibn Hayyan. As William Newman has shown, the text was not actually written by Geber, who was supposed to have lived around the eighth century, but by Paul of Taranto, a Franciscan from southern Italy.Footnote 60 Even though the text contains influences from Arab alchemists, it is not a translation from Arabic but a genuine Latin alchemical text. The great novelty of the Summa is that it represents the launch of corpuscularianism in medieval alchemy. In the twenty-fourth chapter, Pseudo-Geber expounds his corpuscular theory:

Each of these [principles] in genere is of very strong composition and uniform substance. This is so because the particles of earth are united through the smallest particles [per minima] to the aerial, watery, and fiery particles in such a way that none of them can separate from the other during their resolution. But each is resolved with the other on account of the strong union that they mutually have received through the smallest [per minima].Footnote 61

In this excerpt, Pseudo-Geber describes a kind of mixture which is of Aristotelian inspiration but does not strictly adhere to the Aristotelian notion of mixture. According to Pseudo-Geber, minute elementary parts are joined together in the strongest way so as to formulate sulphur and mercury which are the metallic ingredients. Then, corpuscles of sulphur and mercury are combined in order to give metals. These minute elementary corpuscles are the key agents of Pseudo-Geber’s corpuscularianism. As Newman has shown, Pseudo-Geber adopts the Aristotelian theory of elements and the Stageirite’s notion of composition in order to synthesize his corpuscular theory. Yet Pseudo-Geber’s notion of mixture is different from that of Aristotle, since, in terms of Aristotelianism, the Latin term compositio that has been used denotes a juxtaposition and not a genuine homogeneous mixture.Footnote 62

There is still one more term that needs to be examined, that of ‘uniform substance’, which in Latin bears the scripture uniformis substantia. Newman has suggested that Pseudo-Geber has adopted a cluster of words which, although they seem of Aristotelian origin, are employed in a different way. Specifically, the terms omniomera (homoeomera), una substantia and uniformis are not used in the traditional Aristotelian way in order to denote homeomerous bodies – that is, bodies that have the same composition both in their parts and as a whole – but instead they are used to indicate homogeneity.Footnote 63 Newman used the following source for his interpretation:

A true mixture of the dry and humid so that the humid be tempered by the dry and the dry by the humid, and so that this become one substance homoeomerous in all its parts, and temperate between hard and soft, and extensible in contusion, does not occur except by continual mixture of the viscous humid and the subtle earthy through the smallest particles [per minima].Footnote 64

Plausible as this interpretation may be, I would like to add one more element which is pertinent to the material that has been presented thus far. As has been shown, medieval alchemy was confronted with the problem of substantial form and thus the Pseudo-Geberian terminology of una substantia and uniformis substantia might be connected to the aforementioned problem. In light of the evidence that has been adduced, such an interpretation would not be that far-fetched. Namely the term uniformis substantia strongly alludes to such an interpretation, since Pseudo-Geber’s corpuscularianism serves as a solution to the problem of form. In previous decades, most alchemical theories were accused of being capable of affecting only the accidental form of metals while the true substantial form was left intact. Pseudo-Geber’s statements on uniform and one substance make a sound claim that this distinction of forms is not necessary on the ground that the elementary minute corpuscles, through their very strong composition, serve as building blocks of a unified and uniformed body. Thus the mechanical exegesis offered by the corpuscular theory has made the need of substantial form redundant. This is in complete accordance with Pasnau’s previous statement.

Conclusion

It is beyond any doubt that the Sciant artifices, in its entirety, has exerted tremendous influence in the theoretical framework of alchemy during the high Middle Ages. This assertion is further validated and strengthened through this study, which offers evidence on the second argument of Avicenna’s De congelatione. It has become evident that Avicenna’s argument was connected to the problem of substantial form according to which medieval alchemists were incapable of bringing about a true transmutation since they could not affect and change the substantial form of a metal. Furthermore, it has been shown that the aforementioned problem was widespread and occupied the minds of many medieval scholars like Albert the Great, Constantine of Pisa, Thomas Aquinas, Pseudo-Bede and Giles of Rome. All these medieval authors make a clear caveat which connects the notion of substantial form with a true transmutation. Namely a true alchemical transmutation is denoted by the fact that a metal’s substantial form has been converted into the substantial form of another metal and thus a true substantial change has occurred. The opposite result – that is, failure to change the substantial form – was equal to sophistry and fraudulent alchemy.

In this regard, it has also become obvious that Aristotelianism, through Avicenna, has posed great theoretical challenges to medieval alchemy. In light of these difficulties, it is possible that medieval Aristotelianism, through alchemy, partially paved the way for the emergence of corpuscularianism, since it was Aristotle’s substantial form that posed a significant threat to alchemy’s foundations. But as this study demonstrates, medieval alchemy is dynamic in character and is not a monolithic system of thought. Medieval alchemy had the reflexes to react against the difficulties posed by substantial form and proceed with a more micro-level schematic for explaining its procedures which were further bequeathed to the early modern period. The Summa perfectionis of Pseudo-Geber confirms the dynamic character of alchemy since this particular text had a significant and remarkable impact on the atomic and corpuscular theories of many early modern scientists and thinkers. It is well documented, for instance, that both Sennert and Boyle were influenced by Pseudo-Geber’s Summa with respect to their corpuscular theories.Footnote 65 Therefore, as a final note, the audience should be reminded of what we stressed in the introduction to this study, namely that the problem of substantial form should be seen as a ‘bridge’ – indeed – between the Middle Ages and the early modern period since it provides valuable historiographic evidence for the preparation and emergence of corpuscularianism in the latter period.

Acknowledgements

The present essay is part of the Itineraries of Philosophy and Science from Baghdad to Florence: Albert the Great, His Sources and His Legacies (2023–2025) research project financed by the Italian Ministry of University and Research (PRIN 2022, 20225LFCMZ), in the framework of the PNRR M4C2 financed by the European Union – Next Generation EU.

References

1 Maurice De Wulf, Histoire de la philosophie médiévale, Louvain: Institut supérieur de philosophie, 1905, pp. 504–8.

2 Fernand van Steenberghen, La philosophie au XIIIe siècle, Louvain: Publications universitaires de Louvain, 1966; Chiara Crisciani and Claude Gagnon, Alchimie et philosophie au moyen âge: Perspectives et problèmes, Québec: L’Aurore, 1980.

3 Sébastien Moureau, ‘Alchemy in the Latin world’, in Henrik Lagerlund (ed.), Encyclopedia of Medieval Philosophy: Philosophy between 500 and 1500, Dordrecht: Springer, 2011, pp. 56–60.

4 Charles Burnett, ‘Arabic into Latin: the reception of Arabic philosophy into Western Europe’, in Peter Adamson and Richard C. Taylor (eds.), The Cambridge Companion to Arabic Philosophy, Cambridge: Cambridge University Press, 2005, pp. 370–404; Charles Burnett, ‘Arabic philosophical works translated into Latin’, in Robert Pasnau and Christina Joanne van Dyke (eds.), The Cambridge History of Medieval Philosophy, vol. 2, Cambridge: Cambridge University Press, 2010, pp. 814–21.

5 Jill Kraye, Pseudo-Aristotle in the Middle Ages: The Theology and Other Texts, London: University of London and the Warburg Institute, 1986; Alain de Libera, La philosophie médiévale, Paris: PUF, 2004, pp. 358–67; Edward Grant, A History of Natural Philosophy: From the Ancient World to the Nineteenth Century, Cambridge: Cambridge University Press, 2007, pp. 138–42.

6 Meteorologica III, 6, 378a18–b6; and Physics II, 8, 199a15–17.

7 For instance, see William R. Newman, ‘What have we learned from the recent historiography of alchemy?’, Isis (2011) 102(2), pp. 313–21; Lawrence Principe, The Secrets of Alchemy, Chicago: University of Chicago Press, 2013, pp. 35–7, 224 n. 23; Craig Martin, ‘Alchemy and the Renaissance commentary tradition on Meteorologica IV’, Ambix (2004) 51(3), pp. 245–62, 245–51.

8 William R. Newman, ‘Technology and alchemical debate in the Late Middle Ages’, Isis (1989) 80(3), pp. 423–45; Newman, Promethean Ambitions: Alchemy and the Quest to Perfect Nature, Chicago: University of Chicago Press, 2004.

9 Newman, Promethean Ambitions, op. cit. (8), pp. 17–18.

10 Obrist has already referred to substantial form as a problem for medieval alchemy. See Barbara Obrist, ‘Art et nature dans l’alchimie médiévale’, Revue d’histoire des sciences (1996) 49, pp. 215–86, 231–2.

11 Aurélien Robert, ‘Atomism’, in Lagerlund, op. cit. (3), pp. 219–25; Robert, ‘Atomism’, in J. Travis Paasch and Richard Cross (eds.), The Routledge Companion to Medieval Philosophy, London: Routledge, 2021, pp. 184–93.

12 Sébastien Moureau, ‘Min Al-Kimiya Ad Alchimiam: the transmission of alchemy from the Arab-Muslim world to the Latin West in the Middle Ages’, Micrologus (2020) 28, pp. 87–141.

13 Newman, Promethean Ambitions, op. cit. (8), pp. 43–4.

14 Jean-Marc Mandosio and Carla Di Martino, ‘La “Météorologie” d’Avicenne (Kitāb al-Šifā’ V) et sa diffusion dans le monde latin’, in Andreas Speer and Lydia Wegener (eds.), Wissen über Grenzen: Arabisches Wissen und lateinisches Mittelalter, Berlin: de Gruyter, 2006, pp. 406–24, 413–14.

15 Athanasios Rinotas, ‘The Sciant artifices in the work of Albert the Great: towards two kinds of transmutation?’, Early Science and Medicine (2022) 27(1), pp. 57–82.

16 Elisa Rubino and Samuela Pagani, ‘Il De mineralibus di Avicenna tradotto da Alfredo di Shareshill’, Bulletin de philosophie médiévale (2016) 58, pp. 23–87, 43. For the Arabic version of the text see Eric John Holmyard and Desmond Christopher Mandeville (eds. and trs.), Avicennae De congelatione et conglutinatione lapidum: Being Sections of the Kitâb al-Shifâ, The Latin and Arabic Texts, Paris: P. Geuthner, 1927; George Anawati, ‘Avicenne et l’alchimie,’ in Oriente e occidente nel medioevo: Filosofia e scienze: Convegno internazionale, 9–15 aprile 1969, Rome: Accademia Nazionale dei Lincei, 1971, pp. 285–374.

17 Rubino and Pagani, op. cit. (16), p. 44: ‘Hec igitur in illam permutari non poterit, nisi forte in primam reducantur materiam, et sic in aliud, quam prius erat, permutetur.’

18 The translation taken from Newman, Promethean Ambitions, op. cit. (8), p. 37. For the Latin text see Rubino and Pagani, op. cit. (16), p. 43.

19 Since William Newman has extensively dealt with the first Avicennan argument in his studies, I will not focus on it here. For those interested in it see the sources in note 8.

20 Newman, Promethean Ambitions, op. cit. (8), pp. 38–9.

21 Jon McGinnis, Avicenna, Oxford: Oxford University Press, 2009, pp. 86–7.

22 Abraham D. Stone, ‘Avicenna’s theory of primary mixture’, Arabic Sciences and Philosophy: A Historical Journal (2008) 18(1), pp. 99–119.

23 Robert Pasnau, ‘Form, substance, and mechanism’, Philosophical Review (2004) 113(1), pp. 31–88, 34–5, added emphasis.

24 Albertus Magnus Institut, Albertus Magnus und sein System der Wissenschaften: Schlüsseltexte in Übersetzung Lateinisch–Deutsch, Münster: Aschendorff, 2011, p. 29.

25 For Albert’s alchemy see James Riddick Partington, ‘Albertus Magnus on Alchemy’, Ambix (1937) 1, pp. 3–20; Pearl Kibre, ‘Albertus Magnus on Alchemy’, in James Athanasius Weisheipl (ed.), Albertus Magnus and the Sciences: Commemorative Essays 1980, Toronto: Pontifical Institute of Mediaeval Studies, 1980, pp. 187–202; George Anawati, ‘Albert le Grand et l’alchimie’, in Albert Zimmermann (ed.), Albert der Grosse, seine Zeit, sein Werk, seine Wirkung, Berlin and New York: De Gruyter, 1981, pp. 126–33; Robert Halleux, ‘Albert le Grand et l’alchimie’, Revue des sciences philosophiques et théologiques (1982) 66, pp. 57–80; Athanasios Rinotas, ‘Elixir as means of contrasting with nature in Albert the Great’s alchemy’, in Nicola Polloni and Mattia Cipriani (eds.), Fragmented Nature: Medieval Latinate Reasoning on the Natural World and Its Order, London: Routledge, 2022, pp. 173–93.

26 Rinotas, op. cit. (15), pp. 57–82.

27 Albert the Great, De Mineralibus, ed. Auguste Borgnet, Paris: Vives, 1890, lib. III, Tract. i, cap. 9: ‘Sed tunc oportet nos dicere, quod alchimicorum periti operantur sicut periti medicorum: medici enim periti per medicinas purgativas purgant materias corruptas et facile corruptibiles et impedientes sanitatem … Per omnem autem eumdem modum dicemus operari alchimicorum peritos in transmutatione metallorum. Primo enim quidem purgant multum materiam argenti vivi et sulphuris, quam inesse videmus metallis, qua purgata, confortant virtutes materiae quae insunt ei elementales et coelestes ad proportionem mixtionis metalli quod intendunt inducere: et tunc ipsa natura operatur, et non ars, nisi organice, juvando et expediendo, ut diximus: et sic verum aurum et verum argentum educere et facere videntur.’ Translation taken from Albert the Great, Book of Minerals (tr. Dorothy Wyckoff), Oxford: Clarendon Press, 1967, p. 178.

28 Pasnau, op. cit. (23), p. 35.

29 Albert the Great, De Mineralibus, op. cit. (27), lib. III, Tract. i, cap. 7: ‘quia materia nulla ratione est in aliqua rerum naturalium permanente in natura, nisi sit completa per substantialem formam: videmus autem argentum permanere, et stannum, et similiter alia metalla: videbuntur igitur esse completa per substantiales formas.’ Translation taken from Albert the Great, Book of Minerals, op. cit. (27), p. 173.

30 Albert the Great, De Mineralibus, op. cit. (27), lib. III, Tract. I, cap. 8. Translation taken from Albert the Great, Book of Minerals, op. cit. (27), p. 175.

31 Newman, Promethean Ambitions, op. cit. (8), p. 39.

32 Albert the Great, De Mineralibus, op. cit. (27), lib. III, Tract. i, cap. 8: ‘Praeterea alchimicum vix aut nunquam invenimus, sicut dictum est, in toto operantem, sed potius citrino elixir colorat in auri speciem, et albo elixir colorat in argenti similitudinem, studens ut color in igne remaneat et penetret per totum metallum, sicut spiritualis substantia immissa materiae medicinali: et hoc modo operationis potest induci flavus color, substantia metalli remanente.’ Translation taken from Albert the Great, Book of Minerals, op. cit. (27), p. 176.

33 Albert the Great, De Mineralibus, op. cit. (27), lib. III, Tract. I, cap. 9: ‘Qui autem per alba albificant, et per citrina citrinant, manente specie metalli prioris in materia, procul dubio deceptores sunt, et verum aurum et verum argentum non faciunt.’ Translation taken from Albert the Great, Book of Minerals, op. cit. (27), p. 179.

34 Barbara Obrist (ed. and tr.), Constantine of Pisa: The Book of the Secrets of Alchemy, Leiden: Brill, 1990, pp. 6–14.

35 Claude Lafleur, Quatre introductions à la philosophie au XIIIe siècle: Textes critiques et étude historique, Montreal: Institut d’études médiévales, 1988, p. 262.

36 Barbara Obrist, ‘Cosmology and alchemy in an illustrated 13th century alchemical tract: Constantine of Pisa, The Book of the Secrets of Alchemy’, Micrologus (1993) 1, pp. 115–60.

37 Obrist, op. cit. (34), p. 66: ‘quia ut ait Aristoteles in fine quarti Metheororum: “Sciant alchemiste”, et cetera, ubi ait de sophisticis, quia sophiste faciunt operationes ad tingendum corpora, sed non ad perpetuandum, nec ad profundandum, quia ubi est profundatio, ibi perpetuatio, sed ubi non est profundatio, ibi nec perpetuatio; et ideo est ibi apparentia, sed non existentia.’ The translation is my own and based on Obrist’s edition.

38 Antoine Calvet, L’alchimie au moyen âge: XIIe–XVe siècles, Paris: Vrin, 2018, p. 97 n. 4.

39 Obrist, op. cit. (34), p. 85: ‘Sequitur de sophistica. Unde etiam ait Aristoteles in fine quarto Metheorum: “Sciant autem alchimiste” et cetera, quia ipse dicit de inmutationibus coporum, et colorationibus, sed non profundationibus, nec perpetuationibus eorundem. ideo dicit: “Faciunt res extraneas, ut in eis errent homines.” Et dicit etiam: “Ego tantum non credo quod possit unum corpus redigi in aliud nisi reducatur in primam materiam que est mercurius […] Unde sunt quidam qui faciunt apparentiam, sed non existentiam.”’ Translation taken from Obrist, op. cit. (34), p. 249.

40 Obrist, op. cit. (34), p. 87: ‘Sequitur de profundatione. Profundatio ergo est et significatur per ethymoloiam [profundatio est id est] prorsus fundatio, id est funditus inmutatio cum partibus resolutio, inmutando in aliud quod ante non fuit et sic perpetuando, quia numquam potest fieri perpetuatio nisi precedat profundatio. Unde profundatio est sophisticorum euacuatio, quia omnis uana est actio et inutilis operatio in alchimia nisi mediante profundatione reducendo corpus.’

41 For Pseudo-Thomas and alchemy see Chiara Crisciani, ‘Tommaso, pseudo-Tommaso e l’alchimia: Per un’indagine su un corpus alchemico’, in Alessandro Ghisalberti, Antonio Petagine and Rafaelle Rizzello (eds.), Letture e interpretazioni di Tommaso d’Aquino oggi: Cantieri aperti, Atti del convegno inter-nazionale di studio, Milano, 12–13 settembre 2005, Turin: Instituto di filosofia S. Tommaso d’ Aquino, 2007, pp. 103–19.

42 Calvet, op. cit. (38), pp. 92–3.

43 Newman, ‘Technology and alchemical debate in the late Middle Ages’, op. cit. (8), p. 437.

44 Translation taken from Newman, Promethean Ambitions, op. cit. (8), p. 50.

45 Rota has shown that Aquinas’s general position on artificial form and artefacts can be subjected to other interpretations too. For more see Michael Rota, ‘Substance and artifact in Thomas Aquinas’, History of Philosophy Quarterly (2004) 21(3), pp. 241–59.

46 Thomas Aquinas, Commentum in secundum librum sententiarum, 6:451: ‘Ad quintum dicendum, quod ars virtute sua non potest formam substantialem conferre, quod tamen potest virtute naturalis agentis; sicut patet in hoc quod per artem inducitur forma ignis in lignis. Sed quaedam formae substantiales sunt quas nullo modo ars inducere potest, quia propria activa et passiva invenire non potest, sed in his potest aliquid simile facere; sicut alchimistae faciunt aliquid simile auro quantum ad accidentia exteriora; sed tamen non faciunt verum aurum: quia forma substantialis auri non est per calorem ignis quo utuntur alchimistae, sed per calorem solis in loco determinato, ubi viget virtus mineralis: et ideo tale aurum non habet operationem consequentem speciem; et similiter in aliis quae eorum operatione fiunt.’ Latin text and translation taken from Newman, Promethean Ambitions, op. cit. (8), p. 51.

47 Newman, Promethean Ambitions, op. cit. (8), p. 51, original emphasis.

48 Robert Pasnau and Christopher Shields, The Philosophy of Aquinas, 2nd edn, Oxford: Oxford University Press, 2016, pp. 86, 303.

49 Sander W. de Boer, The Science of the Soul: The Commentary Tradition on Aristotle’s De Anima, c.1260–c.1360, Leuven: Leuven University Press, 2013, p. 99.

50 Peter Weigel, Aquinas on Simplicity: An Investigation into the Foundations of His Philosophical Theology, Bern: Lang, 2008, p. 55.

51 Joshua Hochschild, ‘Form, essence, soul: distinguishing principles of thomistic metaphysics’, in Nikolaj Zunic (ed.), Distinctions of Being: Philosophical Approaches to Reality, Washington, DC: American Maritain Association and Catholic University of America Press, 2013, pp. 21–35.

52 Pasnau and Shields, op. cit. (48), p. 66.

53 Pseudo-Bede, Sententiae, sive axiomata philosophica ex Aristotele et aliis praestantibus collecta, una cum brevibus quibusdam explicationibus ac limitationibus, in Jaques-Paul Migne (ed.), PL, vol. 90, Paris: 1850, p. 967a: ‘Alchimistae dicunt quod ex ferro vel cupro potest fieri aurum per eorum artem. Ubi dicitur quod ex ferro vel cupro fit aurum vel argentum apparenter, non autem existenter. Et ratio est, quia per nullam artem forma substantialis potest poni in esse specifico alterius formae.’

54 Giles of Rome, Quodlibeta (ed. Petrus Damasus de Coninck), Louvain, 1646, VIII: ‘In contrarium est: quia vt dicitur in quodam commentario super methauris, quod dicitur esse Auicenne. Sciant artifices alchimie species transmutari non posse: sed similia facere illis possunt. Prima ars non est principium nisi artificialium: sed aurum non est quid artificiale: sed quid naturale. ergo &c.’

55 Giles of Rome, op. cit. (54): ‘non potest esse naturaliter generatio perfectorum metallorum, cuiusmodi sunt aurum & argentum, Potest autem aliqua permutatio fieri in metallis quantum ad colorem: & quantum ad aliqua accidentia. Tamen quantum ad speciem: & quantum ad formas substantiales non possunt per [f. 34’b] mutari metalla nec fieri nisi in proprio loco generationis. & hoc satis videtur innuere auctoritas allegata, que dicitur esse Auicenne.’

56 Thomas Aquinas, Summa theologica, IIa–IIae q. 77 a. 2. ad. 1: ‘Si autem per alchimiam fieret aurum verum, non esset illicitum ipsum pro vero vendere, quia nihil prohibet artem uti aliquibus naturalibus causis ad producendum naturales et verso effectus; sicut Augustinus dicit, in III De trinitate, de his quae arte Daemonum fiunt.’ Latin text and translation taken from Neil Tarrant, ‘Between Aquinas and Eymerich: the Roman Inquisition’s use of Dominican thought in the censorship of alchemy’, Ambix (2018) 65(3), pp. 210–31, 218.

57 Tarrant, op. cit. (56), pp. 216–18.

58 Robert Pasnau, Metaphysical Themes 1274–1671, Oxford: Oxford University Press, 2011, p. 559.

59 My presentation of the Summa relies heavily on the pioneer studies of William Newman, who has extensively dealt with the subject.

60 William R. Newman, ‘New light on the identity of Geber’, Sudhoffs Archiv für die Geschichte der Medizin und der Naturwissenschaften (1985) 69, pp. 76–90; and Newman, ‘The genesis of the Summa perfectionis’, Les archives internationales d’histoire des sciences (1985) 35, pp. 240–302.

61 William R. Newman, The Summa Perfectionis of Pseudo-Geber, A Critical Edition, Translation and Study, Leiden: Brill, 1991, p. 321: ‘ln genere vero dicemus quod unumquodque ipsorum est fortissime compositionis et uniformis substantie, et illud ideo, quoniam in eis per minima partes terree taliter partibus aereis, aqueis, et igneis sunt unite, ut nulla ipsarum alteram in resolutione possit dimittere. Immo quelibet cum qualibet resolvitur propter fortem unionem quam habuerunt adinvicem per mínima.’ Translation taken from Newman, op. cit., p. 663.

62 William R. Newman, Atoms and Alchemy: Chymistry and the Experimental Origins of Scientific Revolution, Chicago: University of Chicago Press, 2006, pp. 26–9; for more details see Newman, op. cit. (61), pp. 143–92.

63 Newman, op. cit. (62), pp. 30–1.

64 Newman, op. cit. (61), pp. 279–80: ‘Sed vera mixtio sicci et humidi, ut humidum contemperetur a sicco et siccum ab humido et fiat hec substantia una in suis partibus omniomera et temperata inter durum et molle et extensiva in contusione, non fit nisi per diuturnam mixtionem humidi viscosi et subtilis terrei per minima.’ Translation taken from Newman, op. cit. (61), p. 645.

65 Newman, op. cit. (62); William R. Newman, ‘The alchemical sources of Robert Boyle’s corpuscular philosophy’, Annals of Science (1996) 53(6), pp. 567–85.