"Oh for the people who speak one's own language," wrote C. S. Lewis, who, in 1925, having just been appointed tutor in English Literature at Oxford, felt uncomfortably alone and misplaced, even ostracized by Oxford's gray venerables. Happily, a year later he bumped into the Professor of Anglo-Saxon, John Ronald Reuel Tolkien, who, to Lewis' delight, did converse in Lewis' tongue. For three solid hours that first day Tolkien discoursed on Norse myths and legends. That encounter marked the genesis of a friendship, the moment, Lewis later was to recall, when someone who feels estranged suddenly cries out: "What? You too? I though I was the only one."

Warnie Lewis (Lewis' brother), Owen Barfield, Nevill Coghill, and, in particular, Charles Williams also spoke the idiom of Lewis and Tolkien -- an idiom that contrasted sharply with that of the modern world. Thus was born what has become one of the most celebrated literary circles in recent times: the Inklings.

Humphrey Carpenter's collective biography, "The Inklings" -- concerned essentially with Lewis, Tolkien, and Williams -- offers a splendid entree into this 20th-century Oxford symposium, which met on Tuesday afternoons at the "Bird and Baby" pub and on Thursday evenings transformed Lewis' sitting room into an Anglo-Saxon mead hall. The conversation, laced with hearty brown brew, alternated with readings from works in progress. Lewis read portions from "Perelandra" and the Narnia books; Williams, from "The Figure of Beatrice," "All Hollows' Eve" and other works; Tolkien, from "The Hobbit" and "The Lord of the Rings."

Carpenter rightfully begins and ends his book with the combative, complex C. S. Lewis, for Lewis' humor and capacity for friendship nurtured by the give-and-take of kindred spirits. Tolkien and Williams were not significantly altered by the group, but Lewis was changed profoundly.

Lewis, as Carpenter admits, is not an easy man to grasp. He donned many masks, refrained from autobiographical comment, preferred his personal life to remain shaded in secrecy. For over 30 years he lived with and supported Mrs. Janie Moore, the mother of a friend killed in the Great War. Though Moore was peevish and perverse, Lewis doggedly abided her. Rumors were rife about their relationship and, though it was probably not romantic or sexual, Lewis chose neither to expand upon it nor to grouse about it.

Concerning the outside world, however, he was not so tight-lipped. He had absolutely no truck with 20th-century gloom and despair. Probably because he had once been an atheist, he fiercely and unrelentingly defended Christianity. Modern literature, modern mores, the modern spirit he loudly decried. His own work -- chiefly "The Screwtape Letters," "Perelandra," the Narnia series, "The Allegory of Love" -- he viewed as fostering the Christian myth in an unbelieving and wayward age.

Carpenter gives less attention to Tolkien, having written the official biography two years ago. He does, however, probe deeply into Tolkien's relationship with Lewis and offers an explanation for its eventual cooling. The men were fundamentally different: Lewis was mercurial; Tolkien, steady as a hobbit; Lewis was Irish and Protestant; Tolkien, English and Roman Catholic.

The fissure was probably initiated when Lewis began to champion Charles Williams, who aroused suspicion, even jealousy, in Tolkien. In old age, Tolkien once referred to Williams as a "witch doctor."

Williams certainly had the makings of a witch doctor. Black magic, white magic, the tetragrammaton, Platonic life forces, Arthurian legends, Christianity -- all of these and many more interests Williams assimilated without a blink. Whether as poet, critic, visionary, or, at the Oxford University Press, a publisher's assistant, Williams inspired either allegiance or distrust from his friends and associates.

By design, "The Inklings" is not a biographical trilogy. Carpenter does treat the lives of his principals separately, but all the time traces the threads of temperament and happenstance that brought and bound them into a loosely knit fraternity of shared tastes and concerns. Nor, like many biographers, does Carpenter forswear literary criticism. He also delves into formidable questions -- How much of Lewis' personality was a pose? Was Lewis happy in his late marriage to Joy Gresham? -- and he does not balk at suggesting sensible, well-documented answers.

But what lifts "The Inklings" above most biographies published today is Carpenter's ability to fuse fact with imaginative perception. Appropriately near the middle of the book, Carpenter recreates, from conversations and diary accounts, a typical Thursday night meeting of the Inklings: Warnie opens the beer, Tolkien lights his pipe, Lewis begins to read (again, Williams is late), and the reader, suddenly a member of the inner circle, may well cry out, as Lewis did: "What? You too?"