Napoleon Hill

Napoleon Hill built the modern success-literature industry out of two enormous books — The Law of Success (1928) and Think and Grow Rich (1937) — both framed as the distilled findings of a twenty-year study of great industrialists commissioned by Andrew Carnegie. Historians have found no evidence for that commission, or for most of Hill’s other biographical claims, and Wikipedia's article describes him as a con man as well as an author. What is not in doubt is the reach: his phrases were promoted relentlessly by his organisation, and they are still promoted daily by the Napoleon Hill Foundation — which is exactly why unsourced aphorisms attach to his name so easily.