What is the earliest instance of a composer/theorist publishing an analysis of his/her own music?

Question

In the final chapter of his Harmonielehre, Arnold Schoenberg analyzes a brief passage from his own compositional output. (You can find it here, on written page 418 [page 432 of the PDF].)

I'm looking for the earliest instance of a composer publishing an analysis of his/her own music.

Ideally the answer(s) will involve a relatively specific analysis. I can imagine, for instance, that a composer in 1100 may have included one of his compositions in a tonary, indicating his own "analysis" of the mode of the piece. This is great to know, but I'm looking for analyses that are a bit more in-depth than this. Think of Hindemith's own analyses, etc. Obviously there's some bit of opinion inherent in my question, but I think it's still clear enough for an acceptable question.

I have a few hypotheses--Descartes, for instance--but I'm curious what the collective knowledge has to share.

Answer 1

The origin of Western music theory starts with Guido de Arezzo, so that would probably be your best answer, 1028 AD

https://en.wikipedia.org/wiki/Guido_of_Arezzo

However, other indigenous/non-western music could very well be early as 1500 BC Mesopotamia or 400 BC China

https://en.wikipedia.org/wiki/Music_theory#Contemporary

Answer 2

The earliest example I can think of a composer specifically analysing a pieces of their own music is Nicola Vicentino in his 1555 treatise L'antica musica ridotta alla moderna prattica. He is actually very detailed. As another answer states this began with Guido d'Arezzo so there is probably an earlier example. Very interesting question!

Answer 3

Well, it seems a hard answer but I will try to do it. I can speak for my own compositions, and my own experiences in harmony devices and scales. I want to split this answer in two: 1) Melody: I have many ways to make a composition. a) Based in a scale: I usually try several scales from differents sources (western traditional scales, Lydian Chromatic Concepts scales, and another ones that I created and I categorized based in the spirit of Lydian Chromatic Concept of George Russell, these are more than 50). b) Randomly: I´m a tenor saxophone player and an amateur guitar and piano player (I use these two harmonic instruments to harmonize my compositions), and I take advantage of not playing in a achademic way the guitar i.e. to play tones in the instrument to make a good melodic line. Then, I analyze the resolutions of the phrases of the melody to achieve the root that leads it and this path guides me to do a better harmonization. 2) Harmony: Well, in this subject I try to write in a paper the possible targets to harmonize a melody, once I have indentify it. If it´s a scale from my own I have a list of chords for all the more than 50 scales that I created. I have an obsession to be the most original than I can and with this in mind I try the usually western chordal approach (II-V-I, II-bII-I, plagal cadence and so) with my own experimentations, but with my mind open to an horizontal traditional way to an vertical non so traditional one (these two concepts arises from Russell´s book also). Well, I can talk about this for hours but I don´t want to bore you and I don´t know if this is the answer that you need. To summarize, freedom it´s my goal and originality.