We've seen that inclinations involve movement toward an agreeable object or away from one that's disagreeable. Depending on whether an inclination is satisfied or not, the result is pleasure or pain. But pleasure and pain are general terms, and in this lecture we want to examine the varieties of more specific affective phenomena called emotions. Like pleasure and pain, some emotions are agreeable and others disagreeable, and they too are passive. But where pleasure and pain are localized, the emotions aren't. When we taste a delicious food, the palate alone – not the entire self – experiences pleasure. A large part of our being remains free, unoccupied. Emotion, by contrast, tends to take over the whole self, absorbing it completely. While the will intervenes to an extent in how emotion is experienced, emotion is by nature invasive.

So we've defined emotion from a double perspective – it's a form of pleasure and pain but is distinct from them because it's expansive rather than localized. Emotion is also an extension of the inclinations, resulting from their success or failure.

A rigorous classification of the emotions is impossible, but the expression “emotion varies with inclination” affords a reasonable starting point. Our method for classifying the emotions is to hypothetically vary the relationship between object and self, so that the latter will pass through different emotions that can be easily observed.

Consider an agreeable object. Depending on whether it approaches or moves away from the self, agreeable or disagreeable emotions will result.