"I foresee it and and yet I rarely carry it out as I foresee it .... It becomes a selective process what part of the accident one chooses to preserve" (quoted in Theories of Modern Art, Chipp & Selz, p. 621). True! I once saw a film of Robert Motherwell and an assistant readying a plate for a run through the press. Motherwell dripped a few last bits of paint onto the plate, looked at it, and had the assistant rub off some -- but not all -- of the excess. It's all about the choices we make as artists and viewers.
One summer in Paris, in 1994, we saw Joan Mitchell's paintings at the Galerie Nationale du Jeu de Paume. It struck me, first, that they were so large that she would need a ladder. Or several. And, second, that she had made no allowance for a mistake. Each brushstroke was accounted for. Here is a close-up of the kind of work I mean, "Two Pianos," from 1980, which is, in full, 110 x 142":
We once lived near a talented and inventive glassblower named Gary Zack. One of his "mistakes," he thought, was a wide shallow bowl, rimmed with colors, with a small abstract glass form clinging from the center to the edge; it was not perfect because, as he was finishing it, it came out of symmetry and pulled slightly to one side. He rejected it; we loved it, and brought it home, and kept it through two moves, but the movers broke it during the third move. The accident was beautiful to us.
So, as I am re-working paintings, I find I make mistakes that I wipe away, and then I make a few that I keep. Here is one of the keepers, a tiny detail, but it adds a fluid line in a rigid spot: