Quick confession: I am bad to books. Mea culpa, mea minima culpa. I mutilate their pages. I scribble notes in margins, I break spines and bend corners. My crammed-to-bursting shelves have made me ruthless. After finishing junk novels, or thrillers that don't thrill, or even some that do, I consign them to the garbage. And that's not all. I have destroyed books with pleasure. I recall with satisfaction the thunks that I produced by hurling my hard-covered "Garp" against a brick wall.

"Illuminated Manuscripts: Masterpieces in Miniature" at the Walters Art Gallery in Baltimore will disturb the hardened hearts of callous book destroyers, and not just because it is a vast and splendid show.

It opens with a curse.

The first volume one encounters -- a large and lovely choir book made in 1290 in northeastern France -- begins with an "anathema," a boldly lettered warning in Latin pledging torments and damnation to potential thieves and vandals.

"Do not mess with me," is the malediction's message. "Do not mess with books."

To medieval Christians, commoners and nobles, monks as well as laymen; to those few who could read; to the masses who could not; and to Islam's warriors, too, books were sacred objects. Books were weapons, books were teachers, books were lights against the dark. They were magical devices able to defeat memory's imperfections. Secular books recorded in their pages the wisdom of the ages. Sacred books made manifest the holy word of God.

On Dec. 6, 1983, one medieval manuscript, "The Gospel Book of Henry the Lion," sold for $11.9 million to a German consortium. That is still an auction record for a work of art. Henry the Lion's book was finished in 1174. Another prayer book, nearly as old, made by the monks at Helmarshausen for Henry the Lion's wife, Mathilde, is in the Baltimore exhibit. It was bought by Henry Walters (1848-1931), who collected most of the 185 books in the exhibition -- he owned more than 700. The first one he acquired cost $35. Now, illuminated manuscripts are very costly.

They were precious, too, when new. Little metal rings attached to the wood boards of their bindings show that many of these manuscripts were once chained to their shelves.

It is not easy to compare the prices of today with those of the Dark Ages. But consider the illuminator's wages, and the cost of gold leaf, and that of the blue pigment, made from lapis lazuli -- and it may be fair to say that 900 years ago an illuminated manuscript cost more than a house.

The preciousness of books is made beautifully apparent here by the "treasure binding" of the "Mondsee Gospels," an 11th-century Romanesque evangelary from Regensburg, in Germany. Its oak boards are adorned with silver and silver gilt, and with small plaques of carved ivory. At the center of the cover is a shimmering rock crystal. It magnifies an image of the crucified Christ drawn on a ground of gold.

One gospel here was illuminated in 1262 by T'oros Roslin, an Armenian artist who humbly notes in a dedication that he has completed the book "with God's help . . . adorning it, inside with pure gold and many colors, and on the outside with precious stones." The gems and gold cost a great deal, but probably not more than the book's large leather pages of smoothed calfskin. A wall label written by Lilian M.C. Randall, the Walters' curator of manuscripts and rare books, notes that "the 156 calfskins required for a two-volume missal in 14th-century England cost more than the scribe's wages, recorded for a wage of 2 pounds a year for two years. Half this amount went for room and board. The remainder was perhaps spent largely at the ale house, a favorite haven for exhausted scribes, judging from the references to the need for slaking one's thirst at the end of many medieval manuscripts."

In the middle of the 12th century, the famous library at the Benedictine abbey of Cluny had 570 volumes. Randall calls that "an extraordinary number." There are 20 million books and pamphlets in the Library of Congress.

Trade paperbacks and magazines and newspapers that wrap the fish; typewriters, junk mail, word processors, copiers, high-speed lithographic presses -- we who drown in words cannot easily imagine the radiance that surrounded books in provincial northern Europe 1,200 years ago.

Imagine wars fought on the question of whether he who borrowed a Bible from a friend had the right to make a copy. In one such Irish conflict, "The War of the Book" initiated by St. Columba, more than 3,000 died, or so the story goes. Eventually the king himself ruled against the saint, and banished young Columba from the Ireland he loved: "To the cow belongs the calf," the king decreed, "to the book belongs the copy."

Imagine an 8th-century Columban monastery -- on Lindisfarne, Iona or some other little island in the windy North Atlantic. The community of hermits is safe for the time being, for the Vikings from the North have not yet begun their depredations. The monks live in "beehive dwellings," tiny igloos made of piled rocks.

In northern Europe, between the fall of Rome and the rise of Charlemagne, it was on such islands that the written word survived.

Imagine oil lamps and candles, the flickerings, the smoke. Imagine an admired scribe copying, with care, letters, words and verses his companions can't decipher. Perhaps a few old scrolls from Roman days have managed to survive. Perhaps some copies of the Vulgate, error-ridden, incomplete, have been carried to the island on the small boats of the time, square-sailed craft constructed of hides stretched over sticks. The monks have memorized the psalms chanted in their chapels, but not many speak the Latin tongue or even know its alphabet. Where are the grammars or the primers that might teach a man to read?

And yet the whole community serves the written word.

The monks who illuminated such Columban Bibles as the Lindisfarne Gospels or the Book of Kells spent months painting the dense traceries of each large initial. The line that they perfected -- with its spinning spirals, reverse twists and complex interlacings -- is like the matter sequestered in the books themselves, linear, intricate and endless. The ornamentation they devised suggests the spirit of their landscape. The golden lines that climb the spines of tooled Moroccan bindings have grown from the ivy tendrils of the sea cliffs of the Hebrides. In intense profusion, tiny leaves and flowers and interwoven vines cling to each square foot of those rocky islands, where, when you raise your eyes, all you see is the vast and misty sea.

Smoothed calfskin is called "vellum," a word that shares a root with "veal."

"Parchment" is produced from the skins of sheep or goats, and takes its name from Pergamum, the city in Asia Minor where the smoothing and whitening of the hides was perfected.

The word that most evokes the magic of the book has to be "illuminate" -- to brighten, to kindle, to make resplendent, to decorate with gold or silver or brilliant colors, to spiritually enlighten; hence "illuminati."

The oldest volume in the Walters exhibition, a Gospel Book from Germany, circa 870, is open to an image of an Evangelist who seems a Mediterranean figure. He wears a Roman robe and a pair of Roman sandals. In his hand he holds not a flat-paged book, or "codex," but a Roman scroll.

In an exhibit nearby is an initial "Q" from a 12th-century New Testament. Its decorations -- painted probably in England at the Rochester Cathedral priory -- suggest a society still partly animist and pagan. The man seated in the "Q," shown at the beginning of this article, has not one head, but two, and both are heads of beasts. The tail of the "Q" is accurately described on the museum's wall label as "a startled (rather than startling) dragon."

Two old traditions blend in many of these handsome early illuminations. One is classical. It is seen in the flowing robes worn by St. Matthew in a gospel book from southern France, circa 1100, and in the columns and the arches of the niche in which he writes. Strange beasts bite their tails in the golden circles at each of the corners of "in principio erat verbum," in a frontispiece from Corvey. It was made at the same time, but its complex decorations, its northern interweavings, suggest a tradition that is not that of Rome.

Although the novice nun Claricia, who was responsible for the "Q" at the beginning of Psalm 51 in a 13th-century German psalter, added to the page a little signed self-portrait, most of the artists represented are anonymous.

Their tiny, graceful pictures show us many wonders, dragons, angels, heavenly cities and the gaping jaws of hell. One miniature -- by the so-called Boucicaut Master seen here in a French copy of Augustine's "The City of God," circa 1415 -- shows what Randall describes as a "detailed view of sinners being poked, force-fed, beaten, boiled and hanged." They are also being roasted. For those who could not read, these books offered pictures -- of Noah's Ark (with the beasts on one deck and the birds on the deck above), of King Arthur's coat of arms, mischievous monkeys, confident crusaders, and of sexy naked women (look at "Bathsheba Receiving King David's Messenger" in a French Book of Hours from 1524).

One Italian miniature on view portrays a sumptuously dressed woman. The marten fur around her neck is set with pearls and rubies. It was not worn for warmth alone, or for fashion, but to attract her fleas.

In "The Martyrdom of Thomas a Becket" from a 13th-century English psalter, two swords cleave the skull of the archbishop. One of the assassins wears a black mask; one of his companions has struck with such force that his sword has bent. The illustration is still remarkably fresh. In 1538, when King Henry VIII decreed the destruction of the saint's portraits and the eradication of his name from all calendars, the owner of this book dutifully covered up the page with a pasted-down paper sheet.

Most of the books in the Walters show, but not all, come from Europe. The Walters' collection of Armenian manuscripts is thought the finest in America. Also on display are miniatures from India, and Persian and Arabic calligraphies of great beauty. Among the antique artifacts accompanying these pages are a lump of lapis lazuli, the papal ring of Pope Sixtus IV (who reigned from 1471 to 1484) and a safe conduct issued by King Edward of England on April 6, 1292.

One of the oldest objects shown is a monumental frontispiece from a medieval gospel book. Its letters are of gold on purple ground. They were drawn 1,000 years ago by the monks at Corvey. Those large and sumptuous shapes with their complex interlacings are difficult to read. They spell in principio erat verbum.

In the beginning was the word.

"Illuminated Manuscripts: Masterpieces in Miniature," which runs through Jan. 13, commemorates the Walters' golden jubilee. The gallery, at Charles and Centre streets, is celebrating its 50th year as a public art museum.