Marcus Aurelius
Author: Marcus Aurelius
Publisher: Penguin Great Ideas (2005)

Remind yourself constantly of all the physicians, now dead, who used to knit their brows over their ailing patients; of all the astrologers who so solemnly predicted their clients' doom; the philosophers who expatiated so endlessly on death or immortality; the great commanders who slew their thousands; the despots who wielded powers of life and death with such terrible arrogance, as if themselves were gods who could never die; the whole cities which have perished completely, Helice, Pompeii, Herculaneum, and others without number.  After that, recall one by one each of your own acquaintances; how one buried another, only to be laid low himself and buried in turn by a third, and all in so brief a space of time.  Observe, in short, how transient and trivial is all mortal life; yesterday a drop of semen, tomorrow a handful of spice or ashes.  Spend, therefore, these fleeting moments on earth as Nature would have you spend them, and then go to your rest with a good grace, as an olive falls in its season, with a blessing for the earth that bore it and a thanksgiving to the tree that gave it life.