The Problem of the Originality of Spinoza's Conception

Despite appearances, the author of the Ethics is probably less innovative than he seems, since he was not the first to analyse the affects as joint manifestations of the mind and the body, or to have introduced a mixed discourse. In his Letter to Elisabeth dated 21 May 1643, Descartes had written that the passions come under the union of the soul and the body, and are explained by this ‘primitive notion’. The passions therefore do not depend solely on the soul or solely on the body, but on soul and body together. Indeed, they have both a physical and a mental aspect, since the soul's emotions generally involve an action of the body. The Cartesian definition therefore keeps mind and body together and involves both at once. Passion is a physical reality as regards its cause and a mental one as regards its effects. That is why it is not explained by the primitive notion of thought or by the primitive notion of extension, but only on the basis of the union. Yet the union implies that we conceive of soul and body as one thing. This is what emerges from Descartes’ Letter to Elisabeth of 28 June 1643, in which he maintains that ‘to conceive of the union between two things is to conceive of them as one single thing’. After meditating on the factors that prove the distinction between soul and body, he invites his correspondent ‘to represent to herself the notion of the union that each always experiences within himself without philosophising, in knowing that he is a single person who has together a body and a thought.’ The authorship of the third discourse of ontological identity therefore belongs to Descartes, who tries to go beyond the dualism of substances to conceptualise a human being in his unity. Yet, among the derived notions that allow us to re-examine this union are the voluntary actions of the soul on the body and the passions.

The concept of passion plays a key role in the Cartesian system, since it demonstrates this union operating under the influence of the institution of nature, and allows us to shed light on its incomprehensible essence.