Psalm 90

Keep your death in mind

Earliest we can find

This is the earliest source we can find for the idea. Said again in 6 books on our list: Seneca, Moral Letters (64 CE), Epictetus, Enchiridion (125 CE), Marcus Aurelius, Meditations (c. 175), Thomas à Kempis, The Imitation of Christ (1427), Michel de Montaigne, Essays (1580) and Oliver Burkeman, Four Thousand Weeks (2021).

1. “So teach us to number our days, that we may apply our hearts unto wisdom.”