Nietzsche

Evil.- Examine the lives of the best and most fruitful people and peoples and ask yourselves whether a tree that is supposed to grow to a proud height can dispense with bad weather and storms; whether misfortune and external resistance, some kinds of hatred, jealousy, stubbornness, mistrust, hardness, avarice, and violence do not belong among the favorable conditions without which any great growth even of virtue is scarcely possible. The poison of which weaker natures perish strengthens the strong--nor do they call it poison.