Idea generation is an integral component of jazz improvising. This article merges theoretical origins and practical experiences through the examination of two seminal works from Pressing and Sudnow. A comparative analysis yields three common sources with distinct characteristics. The greater body of jazz literature supports this potential link between "knowing" and "doing" viewed through the new filter of sources. The discussion concludes with a projection of how the properties of the sources may directly affect contemporary educational practice in jazz improvisation. (Contains 2 figures.)