In his Science of Logic, Hegel treats life as a pure concept. This means that we know what it is to be a living being, and so how to distinguish living from non-living beings, non-empirically. We know it as an implication of the “science of pure thinking” that the Logic develops. The Philosophy of Nature in the Encyclopedia also treats living beings as categorically distinct, and the treatment is also not an empirical one. But it is not derived from the science of pure thinking as such. This suggests that the latter treatment is not absolutely a priori but, as is sometimes said of other aspects of Hegel’s work, “relatively a priori.” (Stated another way, The Philosophy of Nature is philosophy, not natural science.) What “relatively a priori” might mean is the topic here, and the aim is to show by such an analysis the general form of the relation between the Science of Logic and the Encyclopedia. The main point of comparison and contrast will be Kant’s understanding of the relation between “Transcendental Logic,” The Metaphysical First Principles of Natural Science and The Metaphysics of Morals, a similar, albeit quite differently conceived, tri-partite structure to Hegel’s system.