An alternate theory would be that Bebop, like much great art, probably evolved drawing on many sources. An insightful YouTube video has Jimmy Raney, a jazz guitarist of the time and friend of Charlie Parker, describing how Parker would show up at Raney's apartment door in search of refreshment and the music of Béla Bartók, a leading 20th Century Classical Music composer. Raney describes the great knowledge and depth of understanding that Parker had with the music of Bartók and Arnold Schoenberg, in particular Pierrot Lunaire by Schoenberg and the Quartets by Bartók. Raney recounts his comment to Parker that a section from the Scherzo of the Bartók's Fifth Quartet sounded a lot like some of Parker's jazz improvisation.