Symbolism, Imagery, Allegory
Ben Finney is always drawing. Pictures of Sal as a Salamander sitting on her own hair, pictures of himself, cartoons of other characters. Even Sal at one point draws a rather disturbing picture of Mrs. Cadaver being hanged. And finally, Mr. Birkway has his students draw their souls – an unusual but awesome exercise.
So what's with all the drawings? Well, like books, they are totally open to interpretation. Perhaps Mr. Birkway says it best when he explains the drawing he shows to his students in Chapter 32:
Mr. Birkway said that the drawing was bit like symbols. Maybe the artist only intended to draw a vase, and maybe some people look at this picture and see only that vase. That is fine, but if some people look at it and see faces, what is wrong with that? It is faces to that person who is looking at it. And, what is even more magnificent, you might see both. (32.61)
Drawing is a way to express yourself where you don't have to say just what you mean. You can create something that expresses what you mean in a different way. So when Sal and Ben draw their souls as circles with maple leaves in them, it's not because they literally think they have maple leaves hidden somewhere in their chests. It's because that's how they see their souls when they imagine them.