Blues, Jazz, Ragtime, and Stride Piano
Currently I'm fascinated by Fats Waller and Jelly Roll Morton. Waller is considered a master of stride piano, as is his teacher James P. Johnson. Jelly Roll Morton is not considered a stride piano player, but rather one of the founders of jazz. His Jelly Roll Blues (1915) is considered the first published piece of jazz music. Blues and ragtime had existed for decades already in 1915, and stride piano existed from about 1917. Whatever word you want to apply to their styles, both men clearly had a seminal influence on the subsequent development of jazz.
Recently, books have been published containing piano scores for a number of their famous pieces. (Specifically, Thomas "Fats" Waller: The Great Solos 1929-1941, transcribed by Paul Posnak, and Jelly Roll Morton: The Piano Rolls, realized by Artis Wodehouse.)
It's interesting to compare how those two recent books were made.
Memphis Slim, one of the most influential blues pianists in history, was born in 1915, the year Jelly Roll Morton published his Jelly Roll Blues. Although blues had already existed for some time, the pre-Memphis Slim blues has a characteristic sound in which one can hear the roots of stride piano. Memphis Slim transformed the blues; he marked the "speciation point" at which blues branched off from the other common ancestors of blues and jazz.