Sic transit gloria mundi

Sic transit gloria mundi: "Thus passes the glory of the world."

Traditionally, papal coronations are thrice interrupted by a monk (some say barefoot) holding a pole to which is affixed a burning piece of flax. After it finishes burning, the monk announces, "(Pater sancte), sic transit gloria mundi." This is meant to remind the Pope that, despite the grandeur of the ceremony, and the long history of the office, he is a mortal man.

Similarly, the slave holding the crown in a Roman triumph would whisper "Memento homo," literally "Remember (or "be mindful"), human," or more figuratively, "Remember that you are (only) human."