Aristotle, Nicomachean Ethics
H. Rackham, Ed.

As generally understood then, the boaster is a man who pretends to creditable qualities that he does not possess, or possesses in a lesser degree than he makes out, [3] while conversely the self depreciator disclaims or disparages good qualities that he does possess; [4] midway between them is the straightforward sort of man who is sincere both in behavior and in speech, and admits the truth about his own qualifications without either exaggeration or understatement. [5] Each of these things may be done with or without an ulterior motive; but when a man is acting without ulterior motive, his words, actions, and conduct always represent a his true character.¹ [6] Falsehood is in itself base and reprehensible, and truth noble and praiseworthy; and similarly the sincere man who stands between the two extremes is praised, and the insincere of both kinds are blamed, more especially the boaster. Let us discuss each of the two, beginning with the truthful man. [7]

We are speaking not of truthfulness in business relations, nor in matters where honesty and dishonesty are concerned