Suggested to be from Pro Caelio (ch. xix, sec. 45: "...in that branch of study you saw not only his genius shine forth, which frequently, even when it is not nourished by industry, still produces great effects by its own natural vigour...")
More quotes by Cicero
I never cease urging peace, which, however unfair, is better than the justest war in the world.
Every one is least known to himself, and it is very difficult for a man to know himself.
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Most intellectual people do not believe in God, but they fear him just the same.
Innocence in genius, and candor in power, are both noble qualities.
Attribution
Quote text and notes from Wikiquote: Cicero (page history), available under CC BY-SA 4.0. Source quality and labels are our own summary of what Wikiquote records.