"The purpose of life for man is growth, just as the purpose of life for trees and plants is growth. Trees and plants grow automatically and along fixed lines; man will grow as he will. Trees and plants can only develop certain possibilities and characteristics; man can develop any power which has been shown by any person, anywhere. Nothing that is possible in spirit is impossible in flesh and blood. Nothing that man can think is impossible in action. Nothing that man can imagine is impossible of realization. Man is formed for growth, and he is under the necessity of growing. It is essential to his happiness that he should continuously advance. Life without progress becomes unendurable, and the person who ceases from growth must either become imbecile or insane. The greater and more harmonious and well rounded his growth, the happier man will be. There is no possibility in any man that is not in every man; but if they proceed naturally, no two men will grow into the same thing, or be alike. Every man comes into the world with a predisposition to grow along certain lines, and growth is easier for him along those lines than in any other way. This is a wise provision, for it gives endless variety."
-Wallace Wattles, The Science of Being Great