THANK GOD for Christmas, we say, a bright time in winter's bleak night, a time to weave green garlands from the brown earth, to remember that there is goodness in things and goodness in our fellows despite often dismaying evidence to the contrary, and a time to warm ourselves and friends and strangers at the fires of our hearth, to sing and be jolly and enjoy it all. The Yule log, of course, burns out and the fire dies, but the fires kindled in the imagination continue to glow through the season. And that leads us to our favorite subject, books: books to amuse, to instruct, to titillate, to inform, to love - books conceived in one man's imagination, waiting to strike sparks in our own. Our special Christmas issues contain an eclectic (some might say idiosyncratic, and we would not demur) culling of the thousands of titles published over the course of the year. This week Jonathan Yardley writes on sports books, Susan Wood on poetry, Ann Haskell on children's books, and that's by no means all. Our cup of cheer overflows with books of fiction, books of reference, art books, biographies, photography books, antiques books, unique books, reflecting the written word's infinite variety. Today our bookish revels are ended, at least as far as our annual Christmas offerings go; yours, we truly hope, are about to begin. The titles you see below reflect the choices of Book World's editors. Each of us picked one or two or three that we especially liked. We don't claim that they are the "best" books, the most important, the most "serious." We simply say that they are good, that we enjoyed them, and that you or someone you know will enjoy them too.

FALCORNER, by John Cheever (Knopf, $7.95). What happens when a professor of humanities, taxpayer in the 50 per cent bracket, WASP and heroin addict, knocks his brother on the head with a fire iron? He goes to the same prison as his less fortunate brothers. The jailhouse setting of this excellent novel is far removed from those pleasant suburban prisons where Cheever's people customarily gather at the cocktail hour to cut their graceful figures on the thinning ice, but the fall from grace is still observed with the writer's cool eye and wry detachment, and described in the same clear prose.

SAVILLE, by David Storey (Harper & Row, $10). Growing up and growing away, gains and losses, are at the heart of this leisured, austere novel. Colin Saville, born and raised in a coal mining village in Yorkshire, fulfills a generation of family dreams and hopes by gaining admission to grammar school. Education is the key to escape, but freedom turns out to be a lonely reward. Haunting small details of growing and changing live beyond the grim dales of Yorkshire and beyond the novel.

ESSAYS OF E. B. WHITE, (Harper & Row, $12.50) contain some of the finest examples of contemporary, genuinely American prose. White's style incorporates eloquence without affectation, profundity without pomposity, and wit without frivolity or hostility. Like his predecessors, Thoreau and Twain, White's creative, humane and graceful perceptions are an education for the sensibilities.

THE PATH BETWEEN THE SEAS: The Creation of the Panama Canal, 1870-1914, by David McCullough (Simon & Schuster, $14.95). One of the seven wonders of this century is surely the making of the Panama Canal, both for its engineering and its political chicanery. About 30,000 workers died in the process of digging out 100 million cubic yards of dirt which would have formed a tower many times the size of the Tower of Babel. A fascinating and timely story.

HOUSEBOAT DAYS, by John Ashbery (Viking, $7.95). Ashbery's elegant, witty and paradoxical poems glide seemingly without effort from transparency to mystery, as if they were written (and might best be read) in an altered state of consciousness. Ashbery's is a strange but familiarly concrete world of crosscuts and dissolves in which the images are less symbolic than simply there. His poetry is often considered difficult, and it is almost impossible to paraphrase. The answer to that is to relax and let it flow.

SONG OF SOLOMON, by Toni Morrison (Knopf, $8.95). This is a novel of generations: of Macon Dead Jr. known as "Milkman" for reasons his mother knew and his father only guessed at: of the first black baby born - by a sequence of accidents - in a mid-western hospital that people had come to call "No Mercy." He grows up with money among other blacks who have little or none. Finally he strikes out, takes off for the South to try to find something - nominally hidden treasure - but drawn, in fact, by curiosity, a need to learn about his heritage. The novel has a presence and an emotional strength that set it apart, enabling the reader to immerse himself totally, to share the lives of those Morrison writes about. Her style effectively combines simplicity with a special tough beauty.

UNION DUES, by John Sayles (Atlantic Little, Brown, $9.95). This second novel deals perimarily (and from birlliantly varied viewpoints) with the American working class, its relation to the economic and decision-making structures in our society and the traumatic effects of events which reached a sort of climax in that pivotal year, 1963. To say this is, of course, to say nothing about the book's strengths, the author's deceptively smooth style, or his powers in the more routine areas of narrative, dialogue and description.

THE BOOK OF MERLYN: The Unpublished Conclusion to "The Once and Future King," by T. H. White; Prologue by Sylvia Townsend Warner: Illustrations by Trevor Stubley (University of Texas, $9.95). On the eve of his final battle against Mordered. Arthur engages in a sort of Platonic dialogue with Merlyn and a whole cast of talking animals on forms of government, the folly of war, man as an animal species and in relation to his environment. The arguments are (as arguments on these subjects tend to be) largely a matter of rhetoric, but in White's hands the rhetoric is splendid.