I think about everything first. I think about the scenario: the story and the characters, what I'm trying to say and I'll think about that for a couple of days until it's all locked in and then when I get to an instrument it'll just fall out. But the song's kind of all ready there in my head.
There is no "End" to be written, neither can you, like an architect, engrave in stone the day the garden was finished. A painter can frame his picture, a composer can notate his coda, but a garden is always on the move.