Book IV · Chapter 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.