It's the Murphy's Law of procreation: Whatever you planned will not happen that way, be it a full night's sleep or your elaborate holiday extravaganza. And we just don't believe the notion that there's never a good time for someone to get sick or drop your car keys down a flooded storm drain or use the pinking shears on a long-haired cat you're boarding for friends. The perfect time would be at the end of a long weekend that started with you being told that you're getting a significant merit increase as you're leaving for a spa by yourself, and on the way home you stop at a movie theater to see Daniel Day-Lewis in "The Boxer." THAT would be the perfect time for your children to be children in all their messy, wheezy, diaper-leaking, scab-picking, non-tooth-brushing splendor. Because who would care, after three days being massaged and possessing an active fantasy life?