In the Journal of Cycle Research (7:43–48, April, 1958) S.W. and N.E. Gray published “Evidence for a 400-Year Cycle in Human Ability”, which might have been more accurately called “Human Achievement” since ability refers to potential, but the 25,000 lives they reviewed were finished and realized. They took the names of historic personages listed in the 1935 edition of the Columbia Encyclopedia and classified them, without rating or ranking, each as an equivalent unit, according to their occurrence in time; or, more exactly, counting how many individuals, eminent enough to have won inclusion in this encyclopedia, were alive in each decade between 500 B.C. and A.D. 1800. The authors recognize that essentially their data do not cover “human history”, but “the western world and its Mediterranean fringes”.