Now I lay me down to ... contemplate the relative merits of goose down versus duck down in the pillow under my tired head. Once you've reached the exalted realms of down sleeping pillows, you're going to be cradled in softness. But you'll have to pay for that cloud-like comfort, so you might as well know the few but significant differences between duck and goose -- separating the hype from the cold hard facts.

Under their waterproof feathers, geese and ducks have an undercoat of fluffy insulation that looks like hundreds of white -- or gray -- dandelion heads or blobs of cotton, each with a constellation of threads swirling out wildly in all directions. Down is feathery soft but not stiff like feathers, and it has no quills. It insulates so well because it traps air. The larger the cluster the more air it can trap and the longer it will last without fragmenting or compressing. Geese are bigger than ducks and tend to live in colder climates. That means their down clusters are bigger, denser and better at insulation. The down is more substantial and lofts higher. In addition, down from Eider geese and very mature geese creates something called "cling." That means the swirly fibers of each cluster develop microscopic "hooks" that latch the cluster together, for an even denser, more resilient pillow stuffing.

Duck down is perfectly fine, but ducks are smaller than geese and tend to live in milder climates than the Arctic and Siberia. Their down clusters are smaller -- and skimpier -- than the clusters from a mature goose. Duck down isn't as fluffy and it compresses more quickly. The down will still fill a luxurious and comfortable pillow, but at a lower price, for a shorter time and with less loft. Ducks are nowhere near in short supply, so there's never a shortage of duck down on the market. And goose down has been sold as superior and harder to harvest than duck down, so the buying public tends to place a higher value on goose down.