The accidental and on purpose is the stuff work is made of.
Take writing for instance. Jorge Luis Borges, in his essay “A Defense of Kabbalism”, notes how newspapers are accidental in both sound and meaning since each day is different. Poetry, on the other hand, is only accidental in its meaning. The sound, the words chosen, is on purpose. Then, to some religious sects like the Kabbalah, the Bible is both on purpose in sound and meaning. Its perfection of intention is the aim of study and worship.
What could music look like within this vision?
In jazz, the accidentals are the solos. They’re different every time the piece is played. The head of the tune on the other hand is written out and on purpose. And yet sometimes the solos can have material that is on purpose and the head of the tune can have accidentals.
The accidental and on purpose in work is a tangled web. It’s important, however, to untangle and discover what we can and can’t change in our music.