Experience is the name everyone gives to their mistakes. Lady Windermere's Fan

To ordain the future in advance in this way, man must first have learned to distinguish necessary events from chance ones, to think causally, to see and anticipate distant eventualities as if they belonged to the present, to decide with certainty what is the goal and what the means to it, and in general be able to calculate and compute. Genealogy of Morals

The past will not tell us what we ought to do, but... what we ought to avoid. the Revolt of the Masses

“The power and capacity of learning exists in the soul already; and that just as the eye was unable to turn from darkness to light without the whole body, so too the instrument of knowledge can only by the movement of the whole soul be turned from the world of becoming into that of being, and learn by degrees to endure the sight of being, and of the brightest and best of being, or in other words, of the good.” Republic