Diogenes of Sinope | Marcus Aurelius, Book 8.3

<blockquote>3. Alexander and Caius and Pompeius, what are they in comparison with Diogenes and Heraclitus and Socrates? For they were acquainted with things, and their causes [forms], and their matter, and the ruling principles of these men were the same [or conformable to their pursuits]. But as to the others, how many things had they to care for, and to how many things were they slaves!

Source: The Thoughts of the Emperor Marcus Aurelius Antoninus by Marcus Aurelius Antoninus, translated by George Long</blockquote>