Seneca · On old age and death
Letters 26.7
This is what I say to myself, but I would have you think that I have said it to you also. You are younger; but what does that matter? There is no fixed count of our years. You do not know where death awaits you; so be ready for it everywhere.
Seneca, Letters to Lucilius 26.7, translated by Richard Mott Gummere