This part deals with the affects: our feelings, emotions, and imagination. Spinoza laments the fact that most accounts of the affects treat them in a disdainful manner rather than seeking to understand them as a part of the universal laws of nature. Spinoza aims to correct this by treating the affects in a rational way, “just as if it were a question of lines, planes, and bodies” (69).

First, Spinoza distinguishes between instances in which we act and instances in which we are acted upon. The latter are characteristic of the passions, because we experience them as something that happens to us—something we undergo—rather than something we have control over.

Our mind has both adequate and inadequate ideas, the latter of which are “mutilated and confused” (70). Our actions proceed from adequate ideas, while our passions proceed from inadequate ideas. Thus, our affects reflect confused ideas of things rather than clear intellectual knowledge. The more inadequate ideas we have, the more we are affected by passions; the more adequate ideas we have, the more active our mind will be, and the more our reason will dominate our passions.

The body and the mind cannot control each other’s actions; the body’s power of operation resides only in the body, and the mind’s power in the mind.