THE CENTRAL FACTS FROM THE COURSES YOU ALWAYS MEANT TO TAKE, in 25 lectures; Week 2 Day 4 Comedy

It can be a grim business, the academic study of comedy. Students who are made to read Freud on jokes and laughter may never smile again. For a start, it is depressingly difficult to make any true generalisations on the subject. George Bernard Shaw offered: "the popular definition of tragedy is heavy drama in which everyone is killed in the last act, comedy being light drama, in which everyone is married in the last act".

But this shot at definition is even less true of comedy than it is of tragedy. It is not even true of Aristophanes - the earliest comic playwright whose plays we have - let alone of Tom Stoppard or the Marx Brothers.

Aristophanes's comedies in the later fifth century BC were a world away from butlers with cucumber sandwiches. They were totteringly built on zany ideas such as constructing "Cloudcuckooland" in the sky, or rowing to Hades across a river of singing frogs to fetch back a dead poet. The actors wore ugly masks and grotesque padding and, if playing a male role, sported a monstrous leather phallus. The plays were stuffed with obscenity, jibes about current affairs, and fun at the expense of philosophers, composers, tragedians and, above all, politicians. No cow was too sacred, no family too royal, no poet too laureate, no politician too major to escape the bad taste and squishy dung-balls of Aristophanes.

But things changed from this fantastical interference in the contemporary world to the relatively detached gentility of the so-called New Comedy. Athens lost power and confidence, audiences became more prudish and sentimental. Less than 100 years later, the plays called "comedy", exemplified by Menander, were so different that you might wonder why they had the same name. Rich old men are hoodwinked by cheeky slaves, tarts have hearts of gold, babies are lost and found, and boy marries girl in the end. When the Romans came along, they found this kind of comedy ready-made, and took it over into their language, which was still emerging from the linguistic swamp. And so we still have Latin plays by Plautus and Terence (roughly 220-150 BC).

There was not much theatre in the Middle Ages, which was not perhaps the most amusing of eras to be in. "Comedy" came to mean any story with a reassuring ending - hence Dante's Divine Comedy, much of it set among the agonies of hell. With the new age of the Renaissance, Roman comedy sprouted a whole family of transformations - the commedia dell'arte in Italy, Lope de Vega and co in Spain, Moliere in France, and so on. "Comedian" came to mean any actor, and so the Comedie-Francaise can put on innumerable tragedies. Shakespeare, however, broke down the boundaries of the genre irreparably. The Merchant of Venice, for example, is described as a "Comical History"; and if Troillus and Cressida is, as claimed, a comedy, then it is a pretty sour one. It is hardly surprising that old Polonius in Hamlet goes on about "tragical-comical-historical-pastoral."

Yet the comedy of manners and foibles lived on. It perpetuated and endlessly varied its cast of cuckolded husbands, frisky widows, ingenious servants, quack doctors and priests, old retainers, swaggering officers ... and in the end, "anyone for a wedding?"

In this century the label of "comedy" has often been applied with a kind of dark irony by such disturbers of the peace of mind as Durenmatt, Beckett, Ionesco and Pinter. Lately on the home front, in this post-goon era, there has, however, been a return to the old Aristophanic kind of comedy, at least in radio and TV and stand-up routines, if not so much in the theatre (yet). Zany lunacies, cavorting sequences, grossness, ridicule of the great and the bad, especially politicians, parody of every art- form and sacred cow - only the leather phallus is missing. Once again the contemporary world is the shit and comedy is the fan.

Comedy refuses to stand still (or long enough for you to inspect it under the microscope. And if you tear a bit off for close examination, it looks pretty damn unfunny (as Freud, Bergson, Bakhtin and others have so amply demonstrated). The most important general point is that it is not enough to say that comedy is simply any performance that aims to make people laugh. All sorts of buffoonery, and some sorts of sadism or of sad failure, can make people laugh; and yet they are an insult to the name of comedy.

What all comedy does have to do is to use laughter as its access to the hearts and minds of its audience; the desire for laughter is the hunger that comedy caters for. This feast is made possible through laughter, and would be impossible without it. But the laughter is the appetite, not the meal itself, in the hands of an Aristophanes or Moliere or Synge or Chaplin: laughing matters can be serious food for thought.

Tomorrow, Classical Music