Letters from a Stoic 95 : 9

I mean something like this: A scholar will blush for shame, not if he makes a grammatical blunder intentionally, but if he makes it unintentionally; if a physician does not recognize that his patient is failing, he is a much poorer practitioner than if he recognizes the fact and conceals his knowledge. But in this art of living a voluntary mistake is the more shameful. Furthermore, many arts, aye and the most liberal of them all, have their special doctrine, and not mere precepts of advice – the medical profession, for example. There are the different schools of Hippocrates, of Asclepiades, of Themison.