Examine the life of the best and most productive men and nations, and ask yourselves whether a tree which is to grow proudly skywards can dispense with bad weather and storms. Whether misfortune and opposition, or every kind of hatred, jealousy, stubbornness, distrust, severity, greed, and violence do not belong to the favourable conditions without which a great growth even of virtue is hardly possible? The poison by which the weaker nature is destroyed is strengthening to the strong individual and he does not call it poison.