As a Man Thinketh is a literary essay and book by James Allen, published in 1903. It was described by Allen as .. . [dealing] with the power of thought, and particularly with the use and application of thought to happy and beautiful issues. I have tried to make the book simple, so that all can easily grasp and follow its teaching, and put into practice the methods which it advises. It shows how, in his own thought-world, each man holds the key to every condition, good or bad, that enters into his life, and that, by working patiently and intelligently upon his thoughts, he may remake his life, and transform his circumstances.Mind is the Master power that moulds and makes, and man is mind, and evermore he takes the tool of thought, and, shaping what he wills, Brings forth a thousand joys, a thousand ills: - He thinks in secret, and it comes to pass: Environment is but his looking-glass.