“Hence thou must in no manner deny that there is an immutable truth, embracing all such things as are immutably true; a truth which thou canst not call thine, or mine, or any man’s but which is present to all and gives itself to all alike who discern the things that are immutably true, as a light which in some miraculous way is both secret and yet open to all.” ─De Libero Arbitrio, 2, 12, 33.
“Everyone who knows that he is in doubt about something, knows a truth, and in regard to this that he knows he is certain. Therefore he is certain about a truth. Consequently everyone who doubts if there be a truth, has in himself a true thing on which he does not doubt; nor is there any true thing which is not true by truth. Consequently whoever for whatever reason can doubt, ought not to doubt that there is truth.” ─De vera Religione, 39, 73.
“That is was You who taught me, I believe: for it is the truth, and there is no other teacher of truth save You, no matter where or when it may happen to shine.” ─Confessions, 5, 6.
“Nothing conquers except truth: the victory of truth is charity.” ─Sermon, 358, 1.
Polyptych of St Augustine: St Augustine, by Piero della Francesca.
Tempera on panel, c. 1465; Museu Nacional de Arte Antiga, Lisbon.