Spinoza's ethics is grounded by a conviction which is as simple as it is programmatic: Subjective experience can be explained, and its successful explanation is of ethical relevance. For it makes us smarter, freer and happier. This is the programmatic conviction behind Spinoza's ethics and motivates many of the theses it puts forward. Ursula Renz shows which kind of a theory of the human mind informs this program. The systematic differentiation of theory parts in the architecture of ethics proves to be a decisive move: A theory part that deals with questions of the ontology of the mental is followed by a definition of the human mind as a kind of subject theory, which in turn is separated from a theory part dealing with the constitution of content. This structure makes it possible to deal separately with different problems that arise in the course of the explanation of experience. In the end, Spinoza succeeds in avoiding both reductionisms and skepticisms right from the start. In this way, two intuitions are brought together that are often considered incompatible: on the one hand, the view that experience is something irreducibly subjective, and on the other hand, the assumption that there are better and worse explanations of experience.