Letters 58.33

But we shall ask this question also: “Is the extremity of life the dregs, or is it the clearest and purest part of all, provided only that the mind is unimpaired, and the senses, still sound, give their support to the spirit, and the body is not worn out and dead before its time?” For it makes a great deal of difference whether a man is lengthening his life or his death.

Seneca, Letters to Lucilius 58.33, translated by Richard Mott Gummere