I remember one interview in which he said something along the lines of having an aesthetic, emotion or story in mind, but that the rhythm, melody, and vowel sounds are the most important things. Once these are working as a vocal performance, the words then start to condense around the sounds.
It's certainly true in the ancient Irish poetic tradition that the vowel sounds are hugely important to the flow of a piece.
I've started using this method lately, (on a couple of songs that I haven't posted here) and I'm finding that the results seem a lot less forced, and more inspired than simply sitting down with a pencil, paper and guitar.
Many of us say that we don't 'write' our best songs, that instead we seem to simply 'hear' them, or catch them out of the ether. Maybe this is a way of staying in tune with that sort of inspiration throughout the whole writing process?
What say you all?