John Cassian, The Institutes V.41

The saying of Abbot Macarius of the behaviour of a monk as one who was to live for a long while, and as one who was daily at the point of death.

There is still one valuable charge of the blessed Macarius to be brought forward by us, so that a saying of so great a man may close this book of fasts and abstinence. He said then that a monk ought to bestow attention on his fasts, just as if he were going to remain in the flesh for a hundred years; and to curb the motions of the soul, and to forget injuries, and to loathe sadness, and despise sorrows and losses, as if he were daily at the point of death. For in the former case discretion is useful and proper as it causes a monk always to walk with well-balanced care, and does not suffer him by reason of a weakened body to fall from the heights over most dangerous precipices: in the other high-mindedness is most valuable as it will enable him not only to despise the seeming prosperity of this present world, but also not to be crushed by adversity and sorrow, and to despise them as small and paltry matters, since he has the gaze of his mind continually fixed there, whither daily at each moment he believes that he is soon to be summoned.