MARCUS AURELIUS

From Meditations:

Reflect often upon the rapidity with which all existing things, or things coming into existence, sweep past us and are carried away. The great river of Being flows on without pause; its actions forever changing, its causes shifting endlessly, hardly a single thing standing still; while ever at hand looms infinity stretching behind and before -- the abyss in which all things are lost to sight. In such conditions, surely a man were foolish to gasp and fume and fret, as though the time of his troubling could ever be of long continuance.