Plain speaking is a cause of trouble, if the result of it is resentment, which is poison of friendship; but compliance is really the cause of much more trouble, because by indulging his faults it lets a friend plunge into headlong ruin. But the man who is most to blame is he who resents plain speaking and allows flattery to egg him on to his ruin.
 Marcus Tullius Cicero, On Friendship (44 BC). copy citation

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Author Marcus Tullius Cicero
Source On Friendship
Topic friendship flattery
Date 44 BC
Language English
Reference
Note Translated by E. S. Shuckburgh
Weblink http://www.gutenberg.org/files/2808/2808-h/2808-h.htm

Context

“When these are administered in a kindly spirit they ought to be taken in good part. But somehow or other there is truth in what my friend Terence says in his Andria: Compliance gets us friends, plain speaking hate. Plain speaking is a cause of trouble, if the result of it is resentment, which is poison of friendship; but compliance is really the cause of much more trouble, because by indulging his faults it lets a friend plunge into headlong ruin. But the man who is most to blame is he who resents plain speaking and allows flattery to egg him on to his ruin. On this point, then, from first to last there is need of deliberation and care. If we remonstrate, it should be without bitterness; if we reprove, there should be no word of insult. In the matter of compliance” source