The characteristic traits that define jazz music as it was originally conceived cannot be made permanent and static on any score or on any piece of paper. Those traits are specifically the special way rhythm is handled (known as swing) and the treatment of the instruments’ sound (which is something quite different from what is taught in conservatories and academic settings) so that it reflects the vocal capacities shown in the traditional songs of Black Americans (Blues and Gospel). These characteristic traits cannot possibly be set down and captured into a score, as they only appear at the moment of performance in function of the abilities and personality of the artist interpreting the piece. So, the essence of jazz cannot be reflected in a written score, and any attempt to do so would not allow us to properly talk about it, in a strict sense, as a “jazz piece”. It is true that there is a large number of jazz pieces composed by jazz musicians that were conceived to be performed by jazz musicians. However, if those “jazz pieces” were played by a classical music performer, they would never reach the level at which they could be considered as “jazz music”. Moreover, the opposite case, where compositions that were not especially written to be played by jazz bands, can become some of the best jazz if they are interpreted and embellished with the rhythmic and expressive elements mentioned above. That is why, since the very earliest days of jazz, alongside the music coming from African-American tradition (Blues, Gospel, Ragtime and music written by jazz players), we also find the rest of the repertories of jazz bands, with pieces that came from pop music, musical revues, movies, and folk music from Europe and other parts of the world, among other sources.
At heart, what matters in jazz music is not “what you play” but rather “how you play it”. This apparently simple concept, has not fully penetrated into our society. Everyone, from the critics to the general public, has made very serious mistakes in this regard, such as when, at the time, Louis Armstrong was criticized for his extremely successful performance in Hello Dolly!, while the versions of Duke Ellington tunes by Barbara Hendricks were lauded as great jazz. This is not to say Hendricks is anything less than an excellent singer, but her talents are limited to the realm of opera and classical singing.
To be clear, you can play anything in jazz, or almost anything, but if we are talking about real jazz, it must be infused with performances that give the sound that flavor of those traditional African-American songs and that particular, driving rhythm we call swing, because as the great Duke Ellington said: It Don’t Mean A Thing If It Ain’t Got That Swing!
Ricard Gili, Fundació Catalana Jazz Clàssic