But since friendship has nowadays become very mealy-mouthed in freedom of speech, voluble in flattery and silent in rebuke, we can only hear the truth from our enemies.
 Plutarch, Moralia (c. 100 AD). copy citation

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Author Plutarch
Source Moralia
Topic friendship speech
Date c. 100 AD
Language English
Reference
Note Translated by Arthur Richard Shilleto
Weblink http://www.gutenberg.org/files/23639/23639-h/23639-h.htm

Context

“And so Antisthenes 518 said well that those who wish to lead a good life ought to have genuine friends or red-hot enemies; for the former deterred you from what was wrong by reproof, the latter by abuse. But since friendship has nowadays become very mealy-mouthed in freedom of speech, voluble in flattery and silent in rebuke, we can only hear the truth from our enemies. For as Telephus 519 having no surgeon of his own, submitted his wound to be cured by his enemy's spear, so those who cannot procure friendly rebuke must content themselves with the censure of an enemy that hates them, reprehending and castigating their vices, and regard not the animus of the person, but only his matter.” source