Peanuts was not an instant hit. It appeared in seven papers in its 1950 debut, and in 1951 it was still carried in only 35 outlets. A Sunday page was added in 1952, and by 1956 it finally reached the 100-paper mark, having gradually added to the original cluster of characters with Linus, Schroeder, Violet and Pigpen. For all its whimsy and the seeming simplicity of its drawing, Peanuts was a remarkably complex strip in terms of the psychological identities of the characters - the gullible, self-doubting, quintessential loser Charlie Brown; the smug, pre-feminist, crabby Lucy; the philosophical Linus; the creative Schroeder; and, of course, Snoopy, the detached observer, the one true realist among them, capable of laughing, sobbing, growling, typing stories, dreaming and daydreaming, as well as miming his moods and feelings and doing imitations of a bird, a vulture, Lucy, a moose, Beethoven and Mickey Mouse.
As the strip progressed, Snoopy became more and more human, signaled by the fact that he began to walk on two feet in 1956. Even more than Charlie Brown, Snoopy became a superstar - when Schultz once identified the 12 secrets of Peanuts' success, one of them was Snoopy's doghouse, and another was Snoopy himself. The country was swept up in Snoopymania, and ''Happiness is a Warm Puppy'' became an international mantra - as well as a merchandising bonanza. As a result, there is an almost infinite variety of memorabilia available to the collector.
Where to begin? Much of the merchandise exploits the various personas in Snoopy's rich fantasy life. There is the helmet-, goggles- and scarf-wearing World War I aviation ace flying his Sopwith Camel to do battle with his arch-enemy Manfred von Richthofen: the Red Baron. Then there is the nonchalant, sunglasses-sporting Joe Cool Snoopy. These images, and that of the simple, quintessential pooch, appear as and on ceramic banks and figures, rubber and vinyl squeeze toys, Timex watches, vinyl astronaut figures, Mattel pop-up music boxes, a Snoopy chef wind-up toy that flips a disk in a frying pan, a 14-inch plastic guitar, a ''Have Lunch With Snoopy'' dome-top metal lunch box with thermos, an aviator figural music box that plays ''It's a Long Way to Tipperary,'' a ''Snoopy and the Gang'' top, a bean bag, a Snoopy-as-Frankenstein stuffed toy, a Snoopy doghouse candy container, and all manner of Snoopy sheets, towels and bedspreads, though these are just the tip of the iceberg.
The most valuable of all Snoopy collectibles, of course, are examples of the original pen-and-ink comic strip art of the inimitable Charles M. Schultz.
Linda Rosenkrantz has edited Auction magazine and authored 18 books, including ''Cool Names for Babies'' and ''The Baby Name Bible'' (St. Martin's Press; www.babynamebible.com). She cannot answer letters personally.