This analysis has challenged a rather unanimous assumption of current scholarship, which frames ancient descriptions of delirium as mental illness.Footnote ¹ It proposes instead to delimit a specific clinical presentation – hyperactive impaired consciousness – as an alternative category that better describes – with fewer anachronistic theoretical assumptions – most of the cases that scholars have so far perceived as madness. This finding might seem particularly controversial when applied to the Hippocratic corpus, for contrary to an important scholarly tradition,Footnote ² I propose that the vast majority of descriptions are addressing cases of delirium, whereas madness was rarely discussed. Similarly, from the post-Hellenistic sources onwards, although I agree with most scholars that medical texts did discuss madness,Footnote ³ I consider mental illness and wakeful impaired consciousness as two different types of entities that needed to be distinguished.

In light of these findings, the tendency in contemporary scholarship to force a modern construct such as mental illness onto ancient narratives seems to be rather misleading. Indeed, although it is possible to find some coincidences and draw certain parallels, our conception of mental illness is so deeply theory-laden that it can hardly be extrapolated to the ancient medical texts. As a result, when researchers assume the validity of these categories they end up grouping and classifying the ancient material in ways that do not necessarily reflect their original conceptions. Impaired consciousness, conversely, which is clinically closer to our definition of a syndrome rather than to a fully fledged disease, is easier to recognise and presupposes fewer theoretical assumptions.

In this sense, the clear distinction between impaired consciousness and madness presents us with new challenges. Considering the strong emphasis put by the authors (particularly the post-Hellenistic ones) on the differential diagnosis between these two conditions, questions should be raised concerning the relevance of such a distinction. Beyond the evident impact that it had in terms of therapy within medical discourse, contrasting delirium with madness might also have been important in other disciplines.Footnote ⁴

In terms of chronological changes, our analysis of wakeful impaired consciousness in general and phrenitis in particular shows how they were conceived, how their understanding evolved in the studied sources and how the notion of disease mutated in parallel with those changes. Overall, we can see a persistent tension between theory and clinic, and a progressive trend away from concrete symptomatic descriptions towards more abstract conceptualisations.

In the Hippocratic corpus the tension leaned towards the clinical end. Most descriptions of impaired consciousness show a certain laxity in the notion of illness, by giving pre-eminence to thorough and detailed clinical accounts over more abstract association of symptoms with distinct diseases. This is particularly evident in the books of Epidemics, where most cases are comprised of catastases and detailed descriptions (most of them without a specific name). But even in the nosological treatises – where allegedly individual diseases such as phrenitis (and also lethargy) are tackled – the boundaries between the different conditions tend to be less emphasised than in later works. Hippocratic authors grouped phrenitis with other related diseases that required a similar kind of careFootnote ⁵ (particularly with peripneumonia and pleuritis).Footnote ⁶ In this way, the notion of disease that emerges from these authors is loose, non-specific, and it mostly consists of collections of manifestations rather than abstract nosological entities.Footnote ⁷

In post-Hellenistic treatises this emphasis slightly shifts towards theory; we could claim that there was a growing focalisation on certain symptoms, paralleled by a progressive development towards their conceptual abstraction. Of the large Hippocratic list of symptoms, some gained increasing attention, whereas there is growing indifference towards several others. Such is the case of speech disorders and coma vigil, which paled into insignificance (especially in Aretaeus’ work, where the latter is not even described, while in Celsus it appears only once).Footnote ⁸ On the contrary, the relevance of insomnia grew remarkably in close association with the presentation of phrenitis,Footnote ⁹ and so did hallucinations.

As discussed, impaired consciousness in On medicine was directly related to the vanas imagines (hallucinations); however, they were construed as a crucial symptom rather than its main cause. In Aretaeus, perception (aisthêsis) becomes a totally independent principle,Footnote ¹⁰ and it is its impairment (manifested through hallucinations) that triggers diseases with a compromised consciousness. In other words, the growth in relevance of this symptom within the medical discourse is accompanied by a progressively abstract reflection on perceptions.Footnote ¹¹

This process of privileging certain features to the detriment of certain others also reveals the way in which illnesses became better defined notions with stricter boundaries. As Pigeaud has remarked, post-Hellenistic works placed a strong focus on nosological taxonomy. In this way, contrary to the Hippocratic corpus, these treatises put their emphasis on diseases, which were organised into comprehensive classificatory systems based on a restricted number of symptoms.Footnote ¹² Undoubtedly, this novel theoretical framework required adapting the vague and broad notion of impaired consciousness into smaller categories, and encouraged doctors to funnel the complexities of delirium into stricter classifications that often used opposing symptoms as dichotomous sorting criteria:Footnote ¹³ acute versus chronic, with or without fever, wakeful versus somnolent, affecting the head or the heart, etc. This tendency to compartmentalise diseases is present – to a greater or lesser extent – in all the post-Hellenistic authors discussed, and the challenge for these doctors was to adapt the vast Hippocratic clinical diversity to the available classifications and possible explanations, where symptoms, affected organs, physio-pathological mechanisms and treatments were more cohesively grouped. In this sense, Celsus’ encyclopaedism and Aretaeus’ lax eclecticism are different approaches with the same aim.

Galen will take matters further. In his systematisation of the psuchê, perceptions are also an independent activity (or HOF to use our contemporary terminology), but they are not the primary problem. They are vicariously compromised by an affection of the ruling part, a concept with an even higher level of abstraction: it is in the hêgemonikon that the problem actually occurs. Furthermore, the symptom-focused definition of disease turned into an activity-focused one. This author conceived illnesses as the impairment of certain activities (energeiai), which in turn depended on the conditions of the body (diatheseis) that enabled such activities.

The relevance of concrete symptoms as the key elements to define and classify diseases has waned and been replaced by a more abstract concept, namely, the activity. Unlike the post-Hellenistic therapeutic approach, Galen’s method did not target the symptoms but the abnormal diathesis that was hindering a specific energeia. Accordingly, τό γέ τοι τῆς θεραπείας δεόμενον οὐδὲν ἄλλο ἐστὶ πλὴν τῆς βλαπτούσης τὴν ἐνέργειαν διαθέσεως (‘nothing else but the condition (diathesis) that damages the activity (energeia) needs treatment’).Footnote ¹⁴ Thus, diseases were conceptually reframed. The complexities of the diagnosis of phrenitis still required there to be fever and delirium (among other symptoms).Footnote ¹⁵ However, for Galen that implied a combination of θερμότης ὡς ἤδη βλάπτειν ἐνέργειαν (‘heat that was such as to damage an activity (energeia)’)Footnote ¹⁶ – i.e. Galen´s definition of fever – accompanied by πλημμελεῖς … κινήσεις τῆς ἡγεμονικῆς δυνάμεως, ἐπὶ μοχθηροῖς συνίστανται χυμοῖς ἢ δυσκρασίᾳ τῶν κατὰ τὸν ἐγκέφαλον (‘a defective movement of the hegemonic capacities secondary to pernicious humours or duskrasia in the brain’)Footnote ¹⁷ – that is, Galen’s definition of delirium. Thus, the symptoms were only relevant as long as they provided information about the diathesis of the body that was impairing the energeia, whereas the name of the diseases was merely a simplified way to group relevant symptoms. Conveniently, both the excessive heat and the abnormal humours could be targeted by Galenic medicine.

As a matter of fact, up until Galen, treatments were conceived as lists of actions or drugs (getting married, purgation, beatings, changes in illumination, etc.) aimed at palliating symptoms and mainly based on previous experience or common sense. Depending on the notion of disease, such catalogues of instructions were more or less specific for a kind of condition. Only seldom (occasionally with Aretaeus) can one see a physio-pathological rationale behind a specific therapy. It is with Galen that combating the cause becomes the main (and often the only) objective of the treatment, which was strictly informed by his tripartite understanding of disease, where the locus affectus dictated the site of application, and the type and magnitude of the duskrasia indicated the kind and potency of the remedies.Footnote ¹⁸

In other words, Galen – despite his thorough symptomatic accounts – took the tension between theory and clinic to the more abstract end. The Hippocratic writers’ detailed clinical descriptions, and the post-Hellenistic attempts to delimit distinct nosological entities shared a common interest in the patient and their clinical presentations, even if they put a different emphasis on each component. Galen’s approach, on the other hand, regarded the individual as a collection of organs and humours aimed at fulfilling certain activities (energeiai), and most of his attention was focused on finding correlations between impaired activities and alterations in these components.Footnote ¹⁹ In his coherent and cohesive theoretical system, diseases presented symptoms emerging from altered functions in specific bodily parts, which could be explained by mechanisms (mostly humoural), the correction of which required corresponding treatments. (It is in this sense that the focus is placed on theory, and the clinical presentations are only relevant as long as they can reveal the more abstract mechanisms underlying the problem.)

In contrast to the changes in the notion of disease that emerge from the analysis of wakeful impaired consciousness throughout the different periods, there are also features that remained stable. We could argue that what we nowadays designate as delirium could be identified – to a greater or lesser degree – by all the ancient sources under analysis as a variable and intermittent state of abnormal behaviour, often accompanied by altered perceptions, which could sometimes be triggered by wine (and other substances), fever or certain acute conditions. Although it could appear in the midst of longer infirmities (such as diseases of young virgins in the HC or melancholia from the post-Hellenistic sources onwards), it was construed as a recognisable entity that often needed to be distinguished from conditions nowadays identified as mental illness.