WHEN it comes to buttons, there is, without doubt, a general tendency to belittle them. Most of us rate the button for its mere functionality. It has been undermined, anyway, for decades now, by the technological wizardry of the zipper.Even more degradingly, the poor button is habitually mentioned as a model of all that is insignificant or valueless. But then that has been its fate at least as far back as the 12th century. For centuries people have not given a button for things, not cared a button for other things, and dismissed the dismissible as not worth a button. Victorian nonsense-monger Edward Lear, wanting to show how little his desperado-adventurers the Jumblies cared for wise council when they "went to sea in a sieve," wrote: And when the sieve turned round and round And everyone cried, 'You'll all be drowned!' They called aloud, 'Our sieve ain't big, But we don't care a button! We don't care a fig! In a sieve we'll go to sea!' And in the late 18th century, a character in a play was made to say: "My father was an eminent button-maker - but I had a soul above buttons - I panted for a liberal profession" ("Sylvester Daggerwood" by George Colman the Younger). Though there is more than a hint, if ironic, in this remark that a maker of buttons might be respectable, even "eminent who wouldn't feel that they, like the play's character, have "a soul above buttons?" In our own century it would be too easy to conclude that buttons have been reduced almost entirely to the utilitarian. They are mainly plain and anonymous. A chronicler of recent button manufacture even maintains that the ideal button ought not to draw attention to itself. Its role, placed discreetly on a modern garment, is to be the size, substance, and color which renders it least remarkable. At least one exceptional 20th-century artist, however, the much admired potter, Lucie Rie, ran a cottage industry during World War II, making ceramic buttons - a vast array of them - for haute couture. Unfortunately, the British government decided that those difficult years were not the time to be making luxury buttons. It felt that her efforts were not essential to the war effort, and her operations were shut down. It is interesting, though, that here was one fine artistic imagination at work on the button in our prosaic century. In fact, Rie was working within a long tradition. For even if most buttons have been overwhelmingly commonplace, a great many others have been lavished with fantasy, exquisite craftsmanship, high aesthetic aims, fashion, and fun. Actually Rie's are far from being the only buttons of decorative and aesthetic quality made in this century - as the last section of a superb new book, "Buttons" by Diana Epstein and Millicent Safro, splendidly shows. To these authors, who run an establishment called "Tender Buttons" in Manhattan to tempt collectors, buttons are as far from anonymous reticence and invisibility as a crown is from a cloth cap. The buttons in their private collection, ranging mainly from the 18th century until now, are beautifully photographed in color for a dazzling succession of plates in this book. They present persistent evidence that buttons are neither humdrum nor commonplace out of necessity. To Epstein and Safro buttons worth their salt are of a vast kaleidoscope of different types, but are without exception visually intriguing in ways that have little to do with closing or opening gaps in clothing. Most of their buttons are small framed images, either purely abstract, or picturing flowers, birds, people, landscapes, objects - anything. IN truth, many of them, cut off now from their original place down the front of a tunic, coat, or blouse, have little except their undisplayed fastenings at the back to distinguish them from brooches, badges, or even earrings. These buttons are a form of dress jewelry. But what is extraordinary is the way in which their forms and imagery echo their times - the preoccupations, poetry, news, art, and humor of the period in which they were made. So here, in Epstein and Safro's book, are buttons depicting events from the French Revolution; buttons in carved mother-of-pearl showing, like a cartoon strip, a sequence of events in a naive love story; Rococo buttons in which the direct influence of painters like Boucher or Lancret are apparent; silver buttons engraved with dogs or horses; miniature-portrait buttons, the heads and shoulders painted or photographed; buttons depicting the (new) Eiffel Tower, or hot air balloons, or steam engines; Alaskan walrus ivory buttons that are small sculptures of fish, whales, seals and walrus; sinuous Art Nouveau buttons in cast silver, celebrating the symbolic female beauty of the turn of the century with wild luxuriance of hair; "Art Deco" buttons, with powerful color and abstract patterns; brass and vegetable ivory American buttons picturing 1930s film stars Bashful, Happy, Dopey, Grumpy, and all; from three centuries buttons with images made of micromosaics; buttons made of many sorts of plastic; 20th-century buttons known as "goofies" and "realistics" formed to look like anything from halved watermelons to split pea-pods, ping-pong bats and balls, ink bottles, boxing gloves, and blue telephones. In such trifles might be discovered the origins of Pop Art. This sumptuous volume is a celebration of the high potential of the art of button collecting - of the achievements, at least, of two button collectors extraordinaire. The reader/looker is left with no doubt that Diana Epstein and Millicent Safro care a great deal more than a button for buttons.