Willy Ley — German Writer born on October 02, 1906, died on June 24, 1969

Willy Otto Oskar Ley was a German-American science writer, spaceflight advocate, and historian of science who helped to popularize rocketry, spaceflight, and natural history in both Germany and the United States. The crater Ley on the far side of the Moon is named in his honor... (wikipedia)

Ideas, like large rivers, never have just one source.
Just as the water of a river near its mouth, in its final form, is composed largely of many tributaries, so an idea, in its final form, is composed largely of later additions.
The study of an idea is, of necessity, the story of many things.