See De anatomicis administrationibus 1.3.233-4: “At first I too had an assistant to skin the apes, avoiding the task myself as beneath my dignity. Yet when one day I found by the armpit, resting on and united to the muscles, a small piece of flesh which I could not attach to any of them, I decided to skin the next ape carefully myself. ... Having found this muscle, ... I was the more anxious to skin the animals myself” (tr. Singer 1956, p. 8). Far from being burdened with age (ingravescente iam aetate) when he wrote this, Galen was about forty.