The street's still mostly asleep as the sun's not up yet. I stride down the sidewalk, past the doors of another bank. On this one, I see a sign taped to the inside of the plate-glass pane. It says, "Please use other door." I've noticed countless signs like this, on any number of paired doors. Yet today, I wonder for the very first time: Why default so often to the negative, the exclusive, the not-here-sucker-over-there-instead? How come it's so rare to post an inviting welcome on the one that works, announcing, "Please use this door"?