We are all puritans now. over the past two years, Americans have largely stopped spending more money than we had and running up credit-card tabs we couldn't pay off. To a great extent, we've been hectored into behaving more like our parsimonious Pilgrim forebears, whose expression of gratitude we celebrate Nov. 26. But the day after Thanksgiving is Black Friday, the traditional start of the holiday shopping season, and it's in need of all the consumption it can get: conspicuous, ridiculous, tasteless or otherwise. It could take a Snuggie Christmas to keep the economy on the mend. Last holiday season, retailers cut prices so deeply that profits disappeared. Then, for much of the year, shoppers cut back too. "I don't think anyone had ever lived through that big a swing in consumption in such a rapid period of time," says Stephen Sadove, CEO of Saks Inc. This year, savings are up and credit-card use is down, which is good — sort of. Yet keep in mind that the Pilgrims were barely eking out a living, surviving in squalor. They had no access to credit. Thrift is a great virtue, but a little mindless spending this season couldn't hurt.