"Complaisance, though in itself it be scarce reckoned in the number of moral virtues, is that which gives a lustre to every talent a man can be possessed of. It was Plato's advice to an unpolished writer that he should sacrifice to the graces. In the same manner I would advise every man of learning, who would not appear in the world a mere scholar or philosopher, to make himself master of the social virtue which I have here mentioned."

Source : Diogenes Laertius (2015). “Delphi Complete Works of Diogenes Laertius (Illustrated)”, p.145, Delphi Classics

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