Related:

• Aristippus being asked what were the most necessary things for well-born boys to learn, said, "Those things which they will put in practice when they become men.
  -- Diogenes Laertius (c. 200 AD) -- Aristippus, iv...
• It takes a wise man to discover a wise man. -- Diogenes Laertius (c. 200 AD) -- Xenophanes, iii
• Asked from what country he came, he replied, "I am a citizen of the world.
  -- Diogenes Laertius (c. 200 AD) -- Diogenes, vi...
• The apophthegm "Know thyself" is his. -- Diogenes Laertius (c. 200 AD) -- Thales, xiii
• The chief good he has defined to be the exercise of virtue in a perfect life.
  -- Diogenes Laertius (c. 200 AD) -- Aristotle, xiii...
• Be of good cheer," said Diogenes; "I see land." -- Diogenes Laertius (c. 200 AD) -- Diogenes, vi
• Diogenes said once to a person who was showing him a dial, "It is a very useful thing to save a man from being too late for supper.
  -- Diogenes Laertius (c. 200 AD) -- Menedemus, iii...
• When a man reproached him for going into unclean places, he said, "The sun too penetrates into privies, but is not polluted by them.
  -- Diogenes Laertius (c. 200 AD) -- Diogenes, vi...
• When asked what he would take to let a man give him a blow on the head, he said, "A helmet.
  -- Diogenes Laertius (c. 200 AD) -- Diogenes, vi...