Meditations 4.12

A man should always have these two rules in readiness; the one to do only whatever the reason of the ruling and legislating faculty may suggest for the use of men; the other, to change thy opinion, if there is any one at hand who sets thee right and moves thee from any opinion. But this change of opinion must proceed only from a certain persuasion, as of what is just or of common advantage, and the like, not because it appears pleasant or brings reputation.

Marcus Aurelius, Meditations 4.12, translated by George Long

Thou shouldest have these two readinesses always at hand; the one which prompts thee to do only what thy reason in its royal and law-making capacity shall suggest for the good of mankind; the other to change thy mind, if one be near to set thee right, and convert thee from some vain conceit. But this conversion should be the outcome of a persuasion in every case that the thing is just or to the common interest—and some such cause should be the only one—not because it is seemingly pleasant or popular.

Marcus Aurelius, Meditations 4.12, translated by C. R. Haines