This section gets into the nitty gritty of words.
It’s not about the ideas we use them for. It’s about the words themselves.
If a text is a well tended garden and its sentences the plants, bushes, and trees, perhaps we can think of words as the wondrous, seemingly endless varieties of petals and leaves that adorn them.
They are essential, of course, and the more we understand what's going on with them, the better we become at catching nuances of meaning. At saying exactly what we want. And at delighting—or infuriating!—our readers.