Writing In The Key of Tree

I've been reading this really cool book about writing lyrics ("Writing Better Lyrics"), and it talks about writing in the key of the subject matter at hand. So if you're writing lyrics about a pig, you'd write in the key of pig.
This is especially exciting to do. You write, "Key of: _______" at the top with your blank filled in, and write below all the words that come to mind. The more adjectives and nouns that come to mind the better.

You end up with a word bank, and writing your lyrics can be a lot faster with some words already there. Anyway, thought it was a cool method and wanted to share with the interwebbing.