When conquering proconsuls returned to pagan Rome to celebrate their triumph, custom was to assign each of them a slave whose only function was to remind the conqueror that the greatest human glory passes quickly. This slave would crouch in the victorious warrior's chariot, whispering as the conqueror rode along triumphantly: "Remember . . . remember thou art mortal.
Source: Three Minutes by James Keller, M. M., 1950
Contributed by: Zaady