What a man can do and suffer is unknown to himself till some occasion presents itself which draws out the hidden power. Just as one sees not in the water of an unruffled pond the fury and roar with which it can dash down a steep rock without injury to itself, or how high it is capable of rising; or as little as one can suspect the latent heat in ice-cold water.
Arthur SchopenhauerIn youth it is the outward aspect of things that most engages us; while in age, thought or reflection is the predominating qualityof the mind. Hence, youth is the time for poetry, and age is more inclined to philosophy. In practical affairs it is the same: a man shapes his resolutions in youth more by the impression that the outward world makes upon him; whereas, when he is old, it is thought that determines his actions.
Arthur Schopenhauer