Arnold Schoenberg writes in the introduction of his treatise on harmony that one must absolutely be wary of any musician who teaches, for that signifies that he has failed in his career as a musician. In truth, and for diverse reasons, any professor of music understands this remark.
In fact, no high level musician has ever left a treatise behind. When Schoenberg writes this he has fled Nazi Germany and has gone to live in the US, where his talent is not recognized. He teaches music, like Beethoven, at times, when he found himself in financial straits.
Let’s look at this more closely. Bach did not leave a treatise. He left the art of the fugue, 22 fugues written on the same theme, without a single comment. Vivaldi left nothing. Mozart didn’t fare any better. I think only Berlioz left an orchestration treatise, which between you and me is of little interest. In jazz it is the same story: Monk, Bud Powel, Armstrong, Parker, Duke Ellington, Mingus, Wes Montgomery, Bill Evans… nothing, not the slightest word! What's more… these people did not take any classes! For them, the master is the ear.
There is hence two ways to learn:
The first is to follow the theoretical classes given by a professor, with the risk that Schoenberg has pointed out.
The second is to find a “master” and to “absorb him" in silence, that is to say to imitate him to the point where one is capable of him in any situation. Then one must assimilate him, that is to say emerge oneself from what one has swallowed, lest one remain a clone of the “master”. Someone I know, let’s say his name is Marc Martin, a saxophonist, assimilated in that way all of John Coltrane, to the point where he took himself for him and where in effect, both in the notes and in the sound, he was rigorously his clone. One day he is playing with a great organist, and during the concert he accelerates at top speed into Coltrane type passages, just as if he was Coltrane. In the end, the organist turns to him and says: "Great, you play really great! But just one thing: hey Marc, where is Martin?" lol
Further to this, an encounter with a “master” underscores two other difficulties: the first is that one can only understand a master to the extent that one has already understood him, for I know people who didn’t think before they encountered a master, but ever since they have encountered one, they have stopped thinking! I would even go so far as saying that if we are really in presence of a master and a disciple, the disciple must ultimately understand the master better than the master understood himself, else it is a fiasco.
Now we see that the first difficulty is twofold: is the master really a master? Can I measure myself to him or will I remain a disciple all my life? For a disciple who has understood the master no longer quotes him – and that is certainly the sign, for truth belongs to no one in particular.