"Thousands of geniuses live and die undiscovered — either by themselves or by others. But for the Civil War, Lincoln and Grant and Sherman and Sheridan would not have been discovered, nor have risen into notice. ... I have touched upon this matter in a small book which I wrote a generation ago and which I have not published as yet — Captain Stormfield's Visit to Heaven. When Stormfield arrived in heaven he ... was told that ... a shoemaker ... was the most prodigious military genius the planet had ever produced."
January 1, 1970
https://en.wikiquote.org/wiki/Autobiography_of_Mark_Twain