The same intelligence is required to marshal an army in battle and to order a good dinner. The first must be as formidable as possible, the second as pleasant as possible, to the participants.
PlutarchTo make no mistakes is not in the power of man; but from their errors and mistakes the wise and good learn wisdom for the future.
PlutarchWe ought to give our friend pain if it will benefit him, but not to the extent of breaking off our friendship; but just as we make use of some biting medicine that will save and preserve the life of the patient. And so the friend, like a musician, in bringing about an improvement to what is good and expedient, sometimes slackens the chords, sometimes tightens them, and is often pleasant, but always useful.
Plutarch