One way to think it through

"How do I know what I think until I hear what I say?" And yet it's true

Many times I sit down at the computer with a gleam of a plan and a few sentences, but by the time I'm done looking up the details and working through the logic, the original plan is perhaps a little corner of something I hadn't thought of doing. Sometimes I wind up chucking the original notion because it turned out to be wrong.

Update: It works the same way with poems. I start out trying to write something romantic for my wife, and it winds up about God or the kids or who knows what.