She tells this story way better than I do...
Writing is hard. Sarah makes it look easy. Take a look at how she describes the mechanics of a team exercise from the Incremental Development Alliance's Small Developer Boot Camp. She lays out that rather technical set of tasks and rolls right into the real world limitations of the moldering zoning codes you find in most cities these days.
My favorite quote from Sarah:
"Everyone has sexy dreams, but as a developer it’s important to maintain a long-term, monogamous relationship with math."