EVERYBODY knows what summer reading is. It's a

"light" book that you read while you are lying in a hammock. You are sipping something cool in a tall glass. Never mind that it's hard as hell to put a glass down safely while you're dangling in a hammock. Never mind that since the advent of air conditioning most people don't even have hammocks, let alone lie in them amidst the bugs and heat, and read featherweight novels. Never mind also that much summer reading is done by students, and they are choosing books from notably "heavy" lists given them by their English teachers--or that in the 19th century, reading parties would go up in the summer from Oxford to Scotland, a dozen students and a college tutor, and read Plato. Despite all that, we know that summer is when you read fluff. And late each spring, lists of recommended fluff duly appear.

But what about the winter? What do or what should you read then? The obvious answer is that you read the books you got for Christmas. Or if you're like certain members of my family, before Christmas, with clean hands and careful page-turning, you read the books you intend to give others, and afterwards the ones they did give you.

I want to go beyond the obvious answer, and talk about three other kinds of winter reading.

The first is what I would call binge-reading: a one-to- two-day period when you do nothing but lie around and read a single huge book. Winter invites that. Since it's mostly dark and cold outside, there is not the same incentive to be up and doing that there is the rest of the year. On a weekend morning, there may not even be much incentive to get out of bed.

The solution (provided you don't have small children) is once in a while not to. Spend the whole weekend in bed. Reading, of course, not making love--which would be impossible, and appallingly repetitive if it were possible.

In my experience, two kinds of books are specially suited for such a binge. Very long, very great novels, and narrative poems. You read them, of course, in quite different ways. The great novels should be those with exceptionally interesting stories; and in bingeing with one, you forget that time exists, and almost that you yourself exist, and just read on and on. I once spent a particularly nasty January weekend reading all three volumes of The Lord of the Rings. I was so gripped that I not only didn't bother to get up and eat very often, I skipped nearly all the poems Tolkien interpolates, because I wanted to hurry on to the next incident. (Try doing that with TV.) I read all day Saturday, most of the night, and finished somewhat past my usual bedtime on Sunday, having not even touched the Sacred Sunday Paper. I've had similar binges with Anna Karenina, Middlemarch, The Charterhouse of Parma, a pair of Austens, A.T. Wright's Islandia, James' Portrait of a Lady. I might average one a winter.

The weekend with a narrative poem is something I've done rather less often. In fact it may be a more idiosyncratic taste altogether. But I still presume to recommend it. The first time I ever did it was on a sleety, dark Saturday in Durham, North Carolina. The year was 1950. I had an overwhelming urge to forget that I was a graduate student with two papers due. One of my courses was in American poetry, and my room was full of Dickinson, Frost, Edwin Arlington Robinson, and so forth. I happened to pick up Robinson's Tristram, and to read the first few lines aloud.

Three hours later I was still reading aloud--in a mutter, but an expressive mutter. At the cost of a moderately sore throat, I read the whole 4,600 lines before I next slept. During this performance I was, of course, very conscious of myself, since I was playing all the parts, such as King Mark and both Isolts, and constantly making decisions about what tone of voice to use, and how dramatic to make the pauses. I just wasn't conscious of myself as a wretched graduate student with two papers due, only of myself as a vehicle for the poem. In the many years since then, I've only been moved to do this two other times: once with Paradise Lost (I skipped Books XI and XII, and sometimes wish Milton had, too) and once with Hugh MacDiarmid's A Drunk Man Looks at the Thistle. Each remains a memorable occasion.

Why just novels and poems? Well, I have tried such binges with several other kinds of books, and always failed. Once it was the Eleventh Edition of the Britannica, the apogee of encyclopedias in English (though not much good on nuclear energy, etc., since it was published in 1910). But endless short pieces won't do. No spell is created. About 10 a.m. I got up and went for a walk in the rain. A couple of times I have tried it with biographies, the 1,000-page prize-winner kind, and here for me the problem was that the second half of famous people's lives tends to be so much less interesting than the first half. All that boring success. And often enough all that depressing bad health. For someone who likes facts enough, a three-volume history might work. But novels are best.

The second kind of winter reading also derives from the weather. Only here it's not the literal fact of cold and darkness that leads to the choice, but the psychic effect they have. Willa Cather describes it in My Antonia. Her scene is a winter afternoon in Nebraska. Jim Burden is looking at the little town of Black Hawk, so gay and green in the spring. Now every house is stripped of its leafy screen, and stands baldly exposed. "The pale, cold light of the winter sunset did not beautify--it was like the light of truth itself."

In other words, spring and summer are a time for growth and optimism (and here the clich,e about summer reading is apt enough), but winter is a time for fearless realism. In particular, it's a time to think about the coldness and emptiness beyond the seeming blue of our sky. Hence to read sober philosophy. Every man and woman to his or her philosopher, and some would say Spinoza. I would say two fairly recent American philosophers. One is William Ernest Hocking, who loved to raise questions that are ordinarily only raised in church. (And there, of course, the answers are anything but suspense-filled.) I'm thinking especially of a book called The Meaning of Immortality in Human Experience. Hocking doesn't claim to know whether there is such a thing as immortality--though he dares a guess. His concern is with the ways in which it matters whether there is or not. No man ever thought more honestly or clearly on the subject.

The other is a man who taught at Princeton named W.T. Stace. Stace liked to confront questions such as the ethical relativism that dominates educated American thought. (For that matter, it mostly dominates uneducated American thought. People like J. Falwell & Co. tend not to think at all, but simply to repeat thinking done two to four thousand years ago.)

Moral relativity confronted Stace with special force during World War II. It seemed to him that if everything really is relative and therefore simply a matter of personal preference, why wasn't the preference of Germans for Nazism just as valid as the preference of Americans for democracy? After all, people in both countries were ready to die for their views. That's the ultimate test of sincerity. Indeed, if you counted heads, many more Germans died for Nazism than Americans did for democracy, so by a majority vote they win. Stace pondered, and wound up writing a book called The Destiny of Western Man. In it he tries to show that on a perfectly secular basis you can make absolute choices, calling one idea good and another bad. It's fine winter reading. So is his Religion and the Modern Mind.

The third kind of winter reading is much less strenuous--though it, too, is weather-related. Here what signifies is that it gets dark so early that children can't stay out until bedtime playing. Winter is the time to devote whole evenings to reading aloud. I'm not speaking of reading little picture-books to little children, but of reading big books to big children: 7-to 12-year-olds who can read perfectly well themselves, but who like the adult company, and who incidentally learn how to pronounce a lot of words without having to go through the humiliation of asking.

Heroic fantasy is what goes best, being equally thrilling to reader and listener. That genre, which only got its name about 10 years ago, is one of the great riches of the 20th century. Tolkien didn't invent it, or C.S. Lewis, either--it's as old as Beowulf and older--but they were its great propagators. Dozens of writers almost as good (or in the case of Lewis, as good) have followed them. Lloyd Alexander with his five books about Taran of Wales and the Princess Eilonwy. Richard Adams with Watership Down, and William Horwood with Duncton Wood. I would not have believed, until I spent 15 or 20 winter evenings reading Duncton Wood aloud with my daughter Kiki, that I could not only care about moles, but that I could take them almost as seriously as I do Anna Karenina and Vronsky.

Heroic fantasy has become so popular and has so nearly merged on its bad side with cheap magic that one has to pick the books with some care. Tolkien in particular has a crowd of fifth-rate followers. Kiki and I once started an elf-and-dwarf book called The Sword of Shannara that sets some kind of record. The author had so meager an imagination (along with his immense verbosity) that he could stage scene after scene in various forests and never name a tree. Or any plant whatsoever. The villains were always lurking in a mysterious kind of vegetation called "the brush."

In the end I couldn't stand all that anonymous undergrowth and all those overblown adjectives, and quit midway, the only book that Kiki and I never finished. No problem. We went right on to Lolah Burford's The Vision of Stephen, which is a book so strange and terrible and richly imagined that it made up for 10 bales of brush. And after that we went on to Ursula Le Guin's Earthsea trilogy, which is worth 20.

Kiki is 13 now, and reading junky teen-age romances. She's the youngest. I don't even hope to be reading Alan Garner's The Weirdstone of Brisingamen aloud this winter, or to have a fifth chance at C.S. Lewis' The Horse and His Boy. Two daughters and two stepdaughters have heard it with me, and now there will be an interregnum until a new generation. That's a winter loss. But a nice weekend binge with James Gould Cozzens' By Love Possessed looms up, and a modest peek into Alfred North Whitehead, and maybe at long last a mutter through the Iliad. I shall almost dread the arrival of spring and those sun-drenched evenings in the garden.