Writing is where theory evolved into experience, for me. I could apply those abstract formulas to living music and see just how they effected the music. It was the bridge that melded the two together. Once that happened, I had a song that demonstrated those theories. Years later, I can still play those songs. Every time I do, I take another ride through my understanding of that theory... and it all comes to life once again.

As a added bonus... it is all recorded in my muscle memory. This means that even if my rotting brain forgets, my body does not. So as long as I play those songs, the theory is reinforced. (kind of like knitting memories)

Lastly, composing a piece, that really says what you feel, is very up lifting. Making your own music and having people be moved by it is awesome.