“Train yourself to think only those thoughts such that in answer to the sudden question ‘What is in your mind now?’ you could say with immediate frankness whatever it is, this or that: and so your answer can give direct evidence that all your thoughts are straightforward and kindly, the thoughts of a social being who has no regard for the fancies of pleasure or indulgence, for rivalry, malice, suspicion, or anything else that one would blush to admit was in one’s mind.”

— Marcus Aurelius, Meditations 4.4