The Rituals of Dinner is one of those agreeable books intended to demonstrate that the ordinary . things we do every day are completely arbitrary and irrational. Sitting down at the table to eat dinner, for instance. Extremely strange. The ancient Greeks had it right: reclining on couches, propped up on one elbow, eating with one hand off of small individual tables (no plates, no forks). Old paintings to the contrary, Jesus and his disciples followed the same procedure at the Last Supper. As for why you can't spear your food with your knife, the assumption is that it would quickly lead to dinner guests attacking and perhaps eating other guests. Not to cast aspersions on cannibals they have their etiquette too, much more elaborate than ours: ''The Aztec cared intensely how they ate people and also who (sic) they ate, when, and where.'' So did other societies: ''Failure to eat a dead parent might mean poor health, or barrenness, or weak children...people prefer to grind up bones or burn the body to ashes, then eat the powder mixed in a drink, or with, say, mashed banana.''
Margaret Visser, a classics professor at York University in Toronto and author of Much Depends on Dinner, isn't as witty or as full of sly contemporary allusions as Alison Lurie in The Language of Clothes, but Visser has the same knack for revealing what our customs whisper about us behind our backs. And her historical and anthropological range is impressive: She moves easily from medieval kings to Mongol nomads, from the Igbo of Nigeria to the Gogo of Tanzania, from Chinese versus Japanese chopsticks to British versus American wedding cakes to Humphrey Bogart toasting Ingrid Bergman in Casablanca by saying, ''Here's looking at you, kid.'' This is no narrow treatise on manners but a cosmopolitan feast, full of customs bland, spicy, and memorably disgusting.
Visser occasionally belabors the obvious and has inexcusably failed to mention Max Beerbohm's droll essay on hosts and guests while discussing the subject. Yet she's always sensible, clearly demonstrating that everything commonsensical, or sacred, has its history, usually surprisingly short. Forks came in from Italy during the 17th century, gradually replacing fingers, not without alarmed indignation. Lunch established itself circa 1820 after dinner had moved from 11 a.m. to 3 p.m. to evening. She agrees with the historian of manners Norbert Elias that the trajectory of Western etiquette has been from medieval communal exuberance to individual fastidiousness and concealment of bodily functions. We now frown on belching, spitting, or blowing one's nose in the tablecloth. Not so long ago we didn't. In fact, English aristocratic dining rooms were still furnished with chamber pots for convenience during hard-drinking dinners in the early 19th century. Today, as we slouch toward pizza-eating, TV-watching informality at dinner, there are still plenty of taboos. We aren't likely to stop off at the fast-food joint for an order of maggots scraped from exhumed six-day-old corpses considered a delicacy by certain New Guinean tribes. B+