ELEGANCE: A Guide to Quality in Menswear by G. Bruce Boyer (Norton) is a book easily spotted in your store by its arresting cover. It has a painting by fashion artist Tony Kokinos of a handsome fellow in a tux and cummerbund, sporting a red carnation, hands tucked easefully into his trouser pockets. He is the beau ideal of the Boyer man, combining elegance and informality, light years away from the dress- for-success cretin.

Boyer has made a name for himself in the men's rag trade over the past few years with sage and witty advice about dressing in the pages of Town & Country magazine. Never having met this paragon, we hied ourselves to his book-launching party in New York recently. What, we wondered, would someone who makes pronunciamentos on men's clthing (however restrained) be wearing on such an occasion?

The party was held upstairs in Burberry's, the men's clothing store on fashionable East 57th Street, and as the guests waved their gin and tonics to make a point, they threatened rack upon rack of $600 suits. Boyer, bearded and balding, was pointed out across a crowded room and we pulled him aside to fire our question: What have you got on?

"The suit is Brioni, double-breasted, ready-made, light gray Italian flannel, a 14- ounce wool. That's mid-weight. The shirt is custom made, from Hilditch and Key in London, white with a maroon medium stripe and a spread collar. The tie is one I've had for years, can't remember where it's from. It has bar stripes, green, tan and red and it's tied in a four-in-hand knot. There's a plain white handkerchief in the pocket of the suit jacket. The shoes are from Poulson & Skone in London, brown suede with a cap toe and medallion design. The socks are light gray patterned wool from W. Bill on Bond Street in London."

Okay, Boyer, that's all fine. But let's get down to business. Where's your underwear from? "That one is easy. I never wear any undershirts and I get all my shorts from the same place -- boxers from Brooks Brothers." Homer and Lord Byron

THE CALL of journalistic duty took us recently to the Greek Islands of the Ionian Sea between Greece and Italy. The islands we visited were full of literary associations, none more potent for us than those connected with the isle of Ithaca, where king Odysseus reigned before going off to Troy, and to which he returned after his years at sea to rout the unruly suitors and reclaim his throne. The capital of this tiny place is also called Ithaca and we hummed into its beautiful harbor on the local ferryboat, late on a sunny afternoon, feeling not unlike the great wanderer himself. The green mountains plunged precipitously into the sea all along the coastline and we were reminded of the scene in The Odyssey when Telemachus, the son of Odysseus, while hunting for his father, turns down a gift of horses from Nestor, saying that his home island of Ithaca has no pastures to support them. He was right.

We made a literary pilgrimage of another sort on the neighboring island of Kefalonia, where Lord Byron lived for four months before transferring to Missolonghi on the mainland, catching the fever, and expiring. The house in the village of Metaxata where Byron lived was destroyed in the disastrous earthquake of 1953 and a new house has been built in its place. In the back are a pile of stones that appear to be the remains of Byron's abode, which looked out on the Ionian Sea. Inside the new house, a man crouched out of sight, hoping this was not another Oxford student come to call. Not far away is something called Byron's Rock, where he would go during his Kefalonian stay to meditate. On the main road nearby, the poet is commemorated in the manner of the late 20th century: There is a restaurant call Pizzeria Byron. In the Margin

ONE OF the best-selling books of fall is likely to be Jean Auel's The Mammoth Hunters, which carries on the story of a prehistoric clan begun in The Clan of the Cave Bear and continued in The Valley of Horses. The official publication date is Dec. 6 but the book's publisher, Crown, with sounds of cash registers jangling in its ears, is shipping the first printing of half-a-million on Nov. 1. The Clan of the Cave Bear has sold 200,000 in hardback for Crown and nealy 4 million in paperback for Bantam. The Valley of Horses has racked up 350,000 in hardcover and about 3 million in paper. . .

We are happy to see that one of our favorite cookbooks of recent years, Cooking From an Italian Garden by Paola Scaravelli and Jon Cohen, originally published by Holt Rinehart, is being reissued in paperback this month by Harvest/HBJ Books. Paola Scaravelli was brought up in a vegetarian household in Italy, and all the book's recipes are meatless. She and her husband, Jon Cohen, teach at the University of Toronto.u Charles Monaghan writes regularly about food, travel and publishing.