Genius is one percent inspiration and ninety-nine percent perspiration.

c. 1903, quoted by M. A. Rosanoff, Harper's Monthly Magazine [Sept. 1932].

Also in: In: Frank Lewis Dyer, Edison His Life and Inventions (Volume 2)

Variant found in Francis Arthur Jones, The Life of Thomas Alva Edison: Sixty Years of an Inventor's Life (1932), 371: "Genius is two percent inspiration, ninety-eight percent perspiration."