The base is hardly like some plant that grows by itself.
From Deleuze in Expressionism in Philosophy: Spinoza. This line is about the base of a triangle and it gets at some of the marvelous oddity of his writing. The simile here is negative and vague, throwaway, suggesting the image is primitive and rough. We all know plants grow, and whether or not they do so quite by themselves is secondary. So here there's pedagogical velocity, he's allowing a rest point while yet reassuring you that the idea is simple. I think he is at his best in moments like this - of ease and command, of an Aristotelian conviction in the total sensibility of the world. A gesture that gets at the joy of his texts: peeling the skin off a grape, revealing a veiny, pulsing inside, a thing indecipherably frail and certainly alive.