Renewed interest in Platonism and Hermetic soul cosmologies.

Descartes: radical dualism—soul (res cogitans) and body (res extensa).

Human soul seen as seat of reason, will, and self-consciousness.

Debates emerge over animal souls and mechanistic bodies.

Mystical and esoteric views on soul persisted alongside rationalism.

Soul increasingly tied to the concept of personhood.

"Accordingly, seeing that our senses sometimes deceive us, I was willing to suppose that there existed nothing really such as they presented to us; And because some men err in reasoning, and fall into Paralogisms, even on the simplest matters of Geometry, I, convinced that I was as open to error as any other, rejected as false all the reasonings I had hitherto taken for Demonstrations; And finally, when I considered that the very same thoughts (presentations) which we experience when awake may also be experienced when we are asleep, while there is at that time not one of them true, I supposed that all the objects (presentations) that had ever entered into my mind when awake, had in them no more truth than the illusions of my dreams. But immediately upon this I observed that, whilst I thus wished to think that all was false, it was absolutely necessary that I, who thus thought, should be something; And as I observed that this truth, I think, therefore I am, was so certain and of such evidence that no ground of doubt, however extravagant, could be alleged by the Sceptics capable of shaking it, I concluded that I might, without scruple, accept it as the first principle of the philosophy of which I was in search."

(Rene Descartes, Discourse on the Method, 1637)