THE SEQUEL to The Lord of the Rings is actually its prologue, both in narrative time and in the mind of the creator. Spanning vast landscapes and thousands of years, the stories in this book tell us what happened in Tolkien's universe from the beginning of time until that eventful period, late in the Third Age of the world, when Frodo Baggins obtained the fateful ring and (with a little help from his friends) finnally carried it through numerous perils to its destruction in the Crack of Doom.

There is an enormous Tolkien readership, including some who devour his books and read practically no others. I cannot help wondering what the reaction will be among these hard-core fans on September 15, the international publication date when this posthumous volume will certainly become an instant best seller. Unbelievers will scoff because this-quite-digested mass of material is Tolkien and fantasy, hobbit-fanciers may find their loyalities divided because it is Tolkien but contains not a single hobbit, until the very end, when the name of "Frodo the Halfling" appears once and the whole Lord of the Rings cycle is compressed into two pages.

From the viewpoint of the Ring trilogy, what we have in this new volume is a substantial part (one hopes that more can be edited and published from the remaining Tolkien manuscripts) of the Translations from the Elvish to which Bilbo Baggins [WORD ILLEGIBLE] himself for long years after celebrating his eleventy-first birthday and slipping quietly out of hobbit society. Its central and longest part, from which the entire volume takes its name, is the epic tale of the theft and quest of the silmarils, three jewels of extraordinary powers which were made by the hot-tempered elven king and craftsman Feanor and were stolen by Morgoth, a demigod devoted to darkness and chaos, who wised to make himself master of all Middle-earth.

The slow unfolding of this story covers centuries and all sections of the old creation before the earth was changed (one of the things that happen in the various wars chronicled here is that it becomes round.) Titanic forces struggle after building up their strength for centuries to prepare for a gigantic encounter.The central myth, of earthlings banded together under a rash oath to do hopeless battle against a demigod, is one of great power and considerable nobility, with splendidly varied episodes of idyllic love and unearthly joy, wanton destruction and high heroism.

Vast landscapes and towering strongholds are evoked, only to perish in smoke or tidal waves; twisted creatures - orcs and balrogs and firedrakes - lurch blood-maddened through the flames; crabbed dwarves plot small-minded revenge for fancied hurts, and the whole centuries-long, panoramic action works out in massive and intricate variations a single, simple theme: "Love not too well the work of thy hands and the devices of thy heart."

The Silmarillion is the chief book of the collection, but only one; the volume opens with a creation myth of singular beauty, and continues with a rather scholarly dicussion of the varied demigrods who are known as "the Valar, the Powers of the Earth." After the Silmarillion proper comes the Akallabeth, the history of an island (one word hints that it might be Atlantis), where human society rose to a level never seen before or since, and then, through the subtle machinations of Sauron, Morgoth's chief assistant and successor, provoked its own destruction. Finally comes a brief historical treatise Of the Rings of Power and the Third Age, ending with a terse summary of what is treated so lavishly in The Lord of the Rings, mentioning Frodo once and putting him in cosmic context.

To devotees of the more familiar Tolkien (though not so much to those superfans who pore over the appendices) all of this may come as a bit of a shock. The Lord of the Rings is a special kind of fiction, midway between medieval romance and modern novel; The SilmarillionN and those works which accompany it in this volume are altogether a different kind of writing - primitive in some places, rather dry and scholarly in others, primarily epic in style and vision, dealing with the fate of whole peoples and focusing daly momentarily on an occasional key individual. If the Ring trilogy competes for attention mainly with almost-forgotten medieval romances, The Silmarillion demands comparison with Hesiod and The Iliad, Paradise Lost and the Book of Genesis. And although it is unevenly written (the author would surely have revised it before publication had be lived), its best parts stand up well under such comparisons.

What happened to Tolkien's style between The Silmarillion and The Lord of the Rings is told, or at least broadly hinted, in his introduction to the Baliantine edition of The Fellowship of the Ring . After The Hobbit was written but before he began to work on the Ring trilogy.

"But I did not go on with this sequel, for I wished first to complete and set in order the mythology and legends of the Elder Days, which had then been taking shape for some years. I desired to do this for my own satisfaction, and I had little hope that other people would interested in this work, especially since it was primarily linguistic in inspiration and was begun in order to provide the necessary background of 'history' for Elvish tongues.

"When those whose advice and opinion I sought corrected little hope to no hope , I went back to the sequel, encouraged by requests from readers for more information concerning hobbits and their adventures. But the story was drawn irresistibly towards the older world, and became an account of its end and passing away before its beginning and middle had been told."

In other words, Tolkien found an enthusiastic audience for one small corner of his massive vision and no market at all for the greater part of his imaginings. And like a true professional (and a hobbit-fancier himself), he adapted - shrank - his vision to suit the avilable market. One is reminded of Shakespeare, whose magnificent series of historical plays produced, off-hand and almost by accident, a minor character named Falstaff . . .

The vision of the First and Second Ages was already fully formed (it had been accumulating in notebooks since 1917, 20 years before The Hobbit was published), and although he could not publish it as such - never, in fact, put it into final, publishable form - Tolkien continued to tinker with its details through the rest of his life and crammed much of it into the various appendices to The Lord of the Rings. So the contents of this posthumous volume will not come as a complete surprise to Tolkien-lovers, though its tone, content and style have only a tenuous connection with his more familiar work.

The task of excerpting a publishable book from the various fragments left by Tolkien was enthrusted to his son, Christopher, who explains his lengthy, complex role in a brief, unassuming foreword. Christopher Tolkien has also recorded excerpts from The Silmarillion on Caedmon Records (disc TC 1564; cassette, CDL 51564)

As to its importance in the Tolkien canon, even those (misguided, I believe) who prefer the hobbit books to this newly published material must recognize that the myths of the Elder Days are what make their favorite author unique. These early fantasy writings (though they appear belatedly, four years after his death and six decades after the stories were conceived) are fundamental Tolkien, the underpinning without which he would not have been able to produce his later works in the form that we know. For though the matter of the Ring trilogy is peripheral to what is given here - almost an afterthought - the matter of The Silmarillion pervades Tolkien's other fantasies and gives them a flavor unique in that field of writing.

Looked at objectively, Tolkien is not, in fact, a great writer of pure adventure; others are his equal or better at conveying the concrete detail, the breathless excitement of steel clashing with steel, muscles straining in combat, dangers, encountered and overcome - and yet his books are literature while theirs are pastimes, entertainment, something to be read quickly and thrown away. The reason, or at least part of it, is that other writers convey adventure and little else (and after a while, one sword cleaving a helmet begins to look like at the others), while Tolkien's stories take place against a background of measureless dept. Frodo moves in a landscape where others have moved before him through long, busy millennia; he comes at the end of a process that began before the sun and moon were sent aloft; he is a part, small but essential, in a timeless war between the forces of order and disorder, and whether he understands it or not - whether the reader understands it or not - that background is ever-present in the creator's mind and it gives Frodo and company a three-dimensional reality that is seldom found in this kind of writing.

Compared to this historic dept, and the thematic and philosophical unity which it underlies, the other distinctions of the Ring trilogy are relatively insignificant - the richness and variety of invented languages, the intricate geography of Middle-earth, the array of creatures familiar and exotic (orcs and dwarves and elves and hobbits, as well as dogs and horse) that enliven its landscapes - though these alone would make Tolkien unique.

In a commerical sense, those who declined to publish this part of his work in the '30s were surely correct. Our time has not been hospitable to cosmogonies and epics unless they are cleverly disguised as something else. Even today, it is hard to imagine that this work would be accepted by a major publisher if there were any other name on the title page. For that matter, can you imagine Hamlet being welcomed by a modern publisher if it were brought in by an unknown author in anything like its present form? (One can hear the agent on the phone: "Bill, they wonder if you could beef up the Ophelia part of a bit.Maybe a nude bathing scene to prepare for that drowning.")

Artistically, we have been deprived by the forces that postponed publication of The Silmarillion until now and decreed that it would be a posthumous work with no final revisions by the author. What we have is imperfect but magnificent in its best moments. Until this volume appeared, I had felt that Tolkien's greatest service to English letters was his translation of the splendid medieval romance, Sir Gawain and the Green Knight . He has surpassed that work, and that is no small achievement.