A striking feature of Spinoza’s analysis of the human emotions (affectiones), which is the subject of the third part of the Ethics, is its thoroughgoing naturalism. We have already seen this naturalism at work in connection with his analysis of the cognitive capacity of the mind, his mechanistic account of imagination and association, and his Hobbes-inspired rejection of the will in E2. He reaffirms it in the preface to E3, claiming that “the way of understanding the nature of anything, of whatever kind, must … be the same, viz. through the universal laws and rules of Nature.”