Think and Grow Rich is a book written by Napoleon Hill in 1937 and promoted as a personal development and self-improvement book. He claimed to be inspired by a suggestion from business magnate and later-philanthropist Andrew Carnegie. Think and Grow Rich is based on Hill's earlier work The Law of Success, and is the result of more than twenty years of study of many individuals who had amassed personal fortunes. Hill studied their habits and drew some 16 "laws" to be applied to achieve success. Think and Grow Rich condenses them, providing the reader with 14 principles in the form of a "Philosophy of Achievement".