From J.A. Cuddon’s A Dictionary of Literary Terms (Penguin, 1979)
A character for me is any linguistic location of a book toward which a great part of the rest of the text stands as a modifier. Just as the subject of a sentence say, is modified by the predicate, so frequently some character, Emma Bovary for instance, is regarded as a central character in the book because a lot of the language basically and ultimately goes back to modify, be about, Emma Bovary. Now the ideal book would have only one character; it would be like an absolute, idealist system. What we do have are subordinate locales of linguistic energy—other characters—which the words in a book flow toward and come out of. A white whale is a character; mountains in Under the Volcano are characters. Ideas can become characters. Some of the most famous characters in the history of fiction are in that great novel called philosophy. There’s free will and determinism. There’s substance and accident. They have been characters in the history of philosophy from the beginning, and I find them fascinating. Substance is more interesting than most of my friends.
Now why would one adopt such awkward language—why not just talk about character in the traditional sense? The advantage is that you avoid the tendency as a reader to psychologize and fill the work with things that aren’t there. The work is filled with only one thing—words and how they work and how they connect. That, of course, includes the meanings, the sounds, and all the rest. When people ask, “How are you building character?” they sometimes think you’re going around peering at people to decide how you’re going to render something. That isn’t a literary activity. It may be interesting, but the literary activity is constructing a linguistic source on the page
From a fantastic 1978 conversation between John Gardner and William H. Gass.
Metaphors and similes are of great value, in so far as they explain an unknown relation by a known one. Even the more detailed simile which grows into a parable or an allegory, is nothing more than the exhibition of some relation in its simplest, most visible and palpable form. The growth of ideas rests, at bottom, upon similes; because ideas arise by a process of combining the similarities and neglecting the differences between things. Further, intelligence, in the strict sense of the word, ultimately consists in a seizing of relations; and a clear and pure grasp of relations is all the more often attained when the comparison is made between cases that lie wide apart from one another, and between things of quite different nature. As long as a relation is known to me as existing only in a single case, I have but an individual idea of it—in other words, only an intuitive knowledge of it; but as soon as I see the same relation in two different cases, I have a general idea of its whole nature, and this is a deeper and more perfect knowledge.
Since, then, similes and metaphors are such a powerful engine of knowledge, it is a sign of great intelligence in a writer if his similes are unusual and, at the same time, to the point. Aristotle also observes that by far the most important thing to a writer is to have this power of metaphor; for it is a gift which cannot be acquired, and it is a mark of genius.
From The Art of Literature by Arthur Schopenhauer.