“Dear youths, I warn you cherish peace divine,
And in your hearts lay deep these words of mine.”
Pythagoras (-585–-495 BC) ancient Greek mathematician and philosopher
As reported by Heraclides, son of Sarapion, and Diogenes Laërtius, in Lives and Opinions of Eminent Philosophers, "Pythagoras", Sect. 7, in the translation of C. D. Yonge (1853)