According to Orson Swett Marden, everything in man's life, everything in God's universe, is based upon principle, a divine law; and the law of prosperity and abundance is just as definite as the law of gravitation, just as unerring as the principles of mathematics. It is a mental law. Only by thinking abundance can you realize the abundant, prosperous life that is your birthright; in other words, according to your thought will be your life, your supply, or your lack. Your mental attitude will be directed right back at you, every time, in kind.