As a composer, I am often asked how I begin a composition. Do I hear the music first or the text? Do I start with a key? Do I write on a score or play the piano?
It is, of course, different every time. There are many thousands of decisions to be made, both conscious and unconscious, before even approaching the first note of a composition... Certainly thousands more, before its conclusion.
But the most important decisions a composer makes, are those that involve philosophy, not theory. Who am I writing for? Why? Is it my intention to write for the audience, the musician, myself? Is there a greater purpose to be served? Am I serving it?
The aesthetic value of music is almost certainly determined by answering those questions. Therefore, it no longer becomes necessary to ask, 'what note or dissonance will I use,' but 'what picture or message am I trying to convey?' If the message is not clear, it makes little difference what theory has been applied.
Theory, then, gives way to philosophy. It is not enough to say 'I like the way it sounds.' The sound of water is pleasant, but is not what one would necessarily term as "music."
Many people ask, "Is it hard to write music?"
The real difficulty in music composition lies in finding a way to make your music mean something to someone other than yourself.