A quote
It is said: “Philosophy is divided into knowledge and state of mind. For one who has learned and understood what he should do and avoid, is not a wise man until his mind is metamorphosed into the shape of that which he has learned. This third department—that of precept—is compounded from both the others, from dogmas of philosophy and state of mind. Hence it is superfluous as far as the perfecting of virtue is concerned; the other two parts are enough for the purpose.”
Seneca·Letter 94 (§48)·trans. Gummere