Wisdom from the Early Stoics, Zeno of Citium 8

Once when a young man was talking a good deal, he said, "Your ears have slid down and merged in your tongue." 

To the fair youth, who gave it as his opinion that the wise man would not fall in love, his reply was: "Then who can be more hapless than you fair youths?" 

He used to say that even of philosophers the greater number were in most things unwise, while about small and casual things they were quite ignorant. 

And he used to cite the saying of Caphisius, who, when one of his pupils was endeavoring to blow the flute lustily, gave him a slap and told him that to play well does not depend on loudness, though playing loudly may follow upon playing well. 

And to a youth who was talking somewhat saucily his rejoinder was, "I would rather not tell you what I am thinking, my lad."

—Diogenes Laërtius, 7.21