I would compare her [fortune] to an impetuous river that, when turbulent, inundates the plains, ruins trees and buildings, removes earth from this side and places it on the other; every one flies before it, and everything yields to its fury without being able to oppose it.
And yet though it is of such a kind, still when it is quiet, men can make provision against it by dams and banks, so that when it rises it will either go into a canal or its rush will not be so wild and
dangerous.
It happens similarly with fortune, which shows her power where no measures have been taken to resist her, and turns her fury where she knows that no dams or barriers have been made to hold her.

Niccolò Machiavelli, The Prince, Chapter XXV.