Doc Searls on his blog.

So where does [architect] Bill Patrick start, working unassisted by computer?

“I start with the light,” he says. “I say ‘where do we want the light?'”

We wanted our light coming from the direction of our hilltop view toward San Francisco Bay. We also wanted to enjoy that light outdoors as well as inside the house. The result is a lot of glass on every floor facing the Bay, and a deck or balcony outside every room on the Bay side the house. The roof is nearly flat, to maximize interior space within the local limits on roof height above grade, and the whole thing is not only beautiful, but unlike anything else, anywhere. It expresses Bill’s art, and it reflects our original intentions.

In other words, it’s a creation, not a replication or a variation. I also can’t imagine seeing this house as a template for anything else.

The same principle applies for any communicative act – letter, email, text, talk, presentation, etc. Start with the light; with what the purpose of the act is. And work backwards from there.

More here.