Baltasar Gracián (1601-1658), The Art of Worldly Wisdom (Doubleday, 1992, tr. C. Maurer, # 173):
Don't be made of glass in your dealings with others. Even less so in friendship. Some people break very easily revealing how fragile they are. They fill up with resentment and fill others with annoyance. They are more sensitive than the pupils of the eyes, which cannot be touched, either in jest or in earnest. They take offense at motes: beams aren't even necessary. Those who deal with them must use great caution, and never forget their delicacy. The slightest slight annoys them. They are full of themselves, slaves to their own taste (for the sake of which they trample on everything else), and idolaters of their own silly sense of honor.
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