Near the end of Part III, Spinoza takes stock. He thinks he has explained the chief emotions and vacillations of mind arising from desire, joy and sadness.

Chief, not every possible conflict. Affects can combine in indefinitely many ways. He believes the preceding account lets readers see how further variations arise; enumerating them all would satisfy curiosity more than his purpose.

There are still points to note about the definitions. He will set them out again, in order, with explanations inserted where needed.

What the list includes

Desire comes first, then joy, then sadness. Joy is a person’s passage from a lesser to a greater perfection; sadness is the passage in the other direction. Spinoza pauses over the word passage. Joy is not perfection itself.

The list reaches forty-eight definitions, many with additional explanations. It is not simply a catalogue assigning familiar names to independently obvious feelings.

The fourth item is wonder. Spinoza says he does not count it as an affect in its own right. Why include it? Because ordinary usage gives some affects different names when the object is something that astonishes us. A similar reason leads him to include contempt. He omits other related definitions where, to his knowledge, no further affect takes its name from them.

After the twentieth definition, he states the principle openly. He knows that ordinary usage gives these names other meanings. He is concerned with the nature of things, not with explaining words; he borrows names whose usual senses are not wholly unrelated to his intended use. One warning should suffice.

At the thirty-first item, the warning briefly returns: the names of the affects have been chosen with ordinary usage in view, rather than as exact statements of their nature.

One man, several relations

A man is called one kind of uncle by his younger brother’s children and another by his sister’s children; his own children call him father. Chinese kinship vocabulary makes the difference audible.

The man has not changed into three people. What he is called depends on the relation from which someone addresses him.

A name may help identify what we mean without, on its own, defining its nature.

Nothing beyond those three

At the end of the forty-eighth explanation, Spinoza leaves jealousy and further vacillations of mind undefined. They combine affects already defined, and many have no names of their own. Ordinary practical life, he observes, often manages with a broad understanding.

Then he gathers the account together. The affects arise from desire, joy or sadness—or, rather, are nothing beyond these three. Each may receive several names according to different relations and external denominations.

The names multiply as the perspective changes. The explanatory account is trying to identify what those names have in common, not to reproduce a dictionary of everyday feeling.

At the end

After the list comes a general definition of an affect insofar as it is a passion of the mind. Spinoza explains its wording piece by piece.

The final clause includes desire alongside joy and sadness. His explanation ends by saying that he added that clause for this purpose. The part closes with a writer telling us why he put a particular phrase into his definition.