Some, who are satisfied with short hours of rest, have learned to watch for long periods without weariness. Men have learned to run upon the thinnest ropes even when slanting, to carry huge burdens, scarcely within the compass of human strength, or to dive to enormous depths and suffer themselves to remain under the sea without any chance of drawing breath. There are a thousand other instances in which application has conquered all obstacles, and proved that nothing which the mind has set itself to endure is difficult. The men whom I have just mentioned gain either no reward or one that is unworthy of their unwearied application; for what great thing does a man gain by applying his intellect to walking upon a tight rope? or to placing great burdens upon his shoulders? or to keeping sleep from his eyes? or to reaching the bottom of the sea? and yet their patient labour brings all these things to pass for a trifling reward. Shall not we then call in the aid of patience, we whom such a prize awaits, the unbroken calm of a happy life? How great a blessing is it to escape from anger, that chief of all evils, and therewith from frenzy, ferocity, cruelty, and madness, its attendants?