Plutarch, An seni respublica gerenda sit
Harold North Fowler, Ed.

But more statesmanlike than this it is, not merely to avoid, when rebuking them openly and in public, any biting speech which violently represses and humiliates them, but rather in kindly spirit to suggest and inculcate in private to those who have natural ability for public affairs advantageous words and policies, urging them on towards that which is noble, adding brilliancy to their minds, and, after the manner of riding-teachers, [p. 141] enabling them at first to mount the populace when it is tractable and gentle ; then, if the young man fails in any way, not letting him be discouraged, but setting him on his feet and encouraging him, as Aristeides raised up and encouraged Cimon and Mnesiphilus did the like for Themistocles when they were at first disliked and decried in the city as being rash and unrestrained. And there is also a story that when Demosthenes had met with a reverse in the assembly and was disheartened thereby, an aged man who had formerly heard Pericles speak touched him with his hand and told him that he resembled that great man in natural ability and, therefore, had been unjust in condemning himself. And so also when Timotheüs was hissed for being new-fangled and was said to be committing sacrilege upon music, Euripides told him to be of good courage, for in a little while the theatres would be at his feet.