From Robert Paul Wolff’s memoirs (pdf), via The Philosopher’s Stone:

It seems, [Carl] Sandburg began, that two cockroaches, brothers, were riding on a farmer’s cart into town one day, when the cart hit a bump, and they were both thrown off. The first brother fell on a big pile of dung, which is seventh heaven for a cockroach. He settled in, ate himself fat and glossy, and prospered.

The second brother fell into a deep hole, where there was nothing to eat and scarcely any way to get out. Slowly, laboriously, he dragged himself up the side of the hole, repeatedly falling back and starting again. He grew thin and weak, and his shell lost its sheen, becoming dull and discolored.

At long last, by the greatest of effort, he managed to heave himself back onto the road. Looking up, he saw his brother perched happily atop his dung pile. “Brother,” he said, looking up, “You are so fat and sleek. How have you managed to flourish like that?”

His brother looked down disdainfully over the edge of the dung and said, with a smug self-congratulatory smile, “Brains. And hard work.”