He who lets the world, or his own portion of it, choose his plan of life for him, has no need of any other faculty than the ape-like one of imitation. He who chooses his plan for himself, employs all his faculties. He must use observation to see, reasoning and judgment to foresee, activity to gather materials for decision, discrimination to decide, and when he has decided, firmness and self-control to hold to his deliberate decision.
He who knows only his own side of the case, knows little of that.
Leonardo da Vinci·1500Iron rusts from disuse; stagnant water loses its purity and in cold weather becomes frozen; even so does inaction sap the vigor of the mind.
Thomas Jefferson·1786If the body be feeble, the mind will not be strong. The sovereign invigorator of the body is exercise, and of all the exercises walking is best. A horse gives but a kind of half exercise, and a carriage is no better than a cradle.
Seneca·60 CE ADThe mind must be given relaxation — it will rise improved and sharper after a good rest. Just as we must not force fertile farmland, for uninterrupted productivity will soon exhaust it, so constant effort will sap our mental vigor.
