Therefore we should not try to alter circumstances but to adapt ourselves to them as they really are, just as sailors do. They don't try to change the winds or the sea but ensure that they are always ready to adapt themselves to conditions. In a flat calm they use the oars; with a following breeze they hoist full sail; in a head wind they shorten sail or heave to. Adapt yourself to circumstances in the same way.
As quoted by Teles of Megara, fr. 2, On Self-Sufficiency