Think of your many years of procrastination; how the gods have repeatedly granted you further periods of grace, of which you have taken no advantage. It is time now to realise the nature of the universe to which you belong, and to that controlling Power whose offspring you are; and to understand that your time has a limit set to it. Use it, then, to advance your enlightenment; or it will be gone, and never in your power again.
Marcus Aurelius, Book II, 4. Meditations.