“Those fortunes that turn out in the contrary way restrict and even ruin one’s blessedness, for they both inflict pains and impede many activities.
Nevertheless, even in the midst of these, nobility shines through, whenever someone bears up calmly under many great misfortunes, not because of any insensitivity to pain but because he is wellborn and great souled. …
For we suppose that someone who is truly good and sensible bears up under all fortunes in a becoming way and always does what is noblest given the circumstances, just as a good general makes use, with the greatest military skill, of the army he has. …
And if this is so, the happy person would never become wretched. … He would not be unstable and subject to reversals either, for he will not be easily moved from happiness, and then not by any random misfortunes but only by great and numerous ones.”
(Nicomachean Ethics, I.10)
Aristotle on the roles of virtue and fortune