IN ENGLISH EXAMS they used to give you a picture - perhaps they still do. A photograph of a beggar, say, or of a circus was supposed to trigger Creative Writing - an essay, a story, or even a poem. Last week, in the inventive Postscript (R3) series, five writers had the run of the National Gallery in which to play the same game: they were in a very different league.

Word Pictures became a magical, powerful synthesis of several arts, centuries and cultures. For example: Sassetta delivered his altarpiece to the church of St Francis in Sansepolcro in 1244, when the saint had been dead only 18 years. In what, therefore, amounted to reportage, it depicted scenes from his life in nine extraordinary, numinous panels. So far, so good. It might encourage emulation in the viewer: Sassetta's skill must excite admiration. Then, in London, Peter Porter chose it and wrote off seven centuries of enigmatic silence.

In Porter's poem, St Francis lives in the paintings and speaks from the gallery walls. He watches people promenading past him, guides misinterpreting him. Glad to be out of earthquake country, he offers his own account of the sequence, using our contemporary vernacular. Here, giving his gorgeous aquamarine cloak to a beggar, he remembers his state-of-the-art spurs; there, shaking hands with a wolf, he announces the beginning of ecology. And Francis/Porter admonishes his sceptical audience: "What seems so quaint to you was touchy-feely to Sassetta". He forbids us to patronise the artist or his subject: he humbles and instructs us.

And the poet and the painter and the stigmatised saint; and whoever gave the picture to the gallery; and the producer, David Perry, and whoever commissioned the series - all of them contribute to that tiny, important, plosive expansion of understanding, that glimpse of a community with history which makes the world a little less hostile, which is the real function of art.

Just as remarkable were Marina Warner's essay on Coreggio, Peter Levi's on Claude and AS Byatt's on Velasquez. None offered a predictable or conventional response to the paintings: all invited the listener to travel with them into remote and exotic landscapes of the mind.

In an even more arcane league is Between The Ears (R3). Gould, Tobacco, Bach managed to connect Glenn Gould the pianist (whose father was called Gold) to the brown vegetal gold (ie tobacco) which was discovered but ignored by Columbus, to the smoker and composer JS Bach - and then back again, via Bach's piano music, which is hurtling into space aboard Voyager in a recording by Glenn Gould. An audible thread unravelled around these disparate landmarks via a UN spokesman, a chemistry lesson and the death of the piano concerto, right up to a Canadian chiropractor from Gould's home town. If Word Pictures is intoxicating, Between the Ears is hallucinogenic.

And Love 40 - New Balls Please (R2) is funny. It's not hilarious or even very original, but it provokes a welcome chuckle, rare in any new sitcom. The sit is Mervyn Stutter's surprise 40th birthday party; the com is in the writing, which tends towards triple-effect bathos (his false prophets are Che Guevara, Elvis Presley and Sooty and Sweep; his mentors Descartes, Jung and Cat Stevens). But it's likeable and accurately aimed. When Mervyn wonders, pretentiously, if a modicum bigger than a soupcon, his wife asks if they're talking modicum estate or GX; when he complains, from the locked loo, that the noisy guests are closet R2 listeners, she patiently replies that they simply want to urinate - "it's not a class issue - it's a bladder thing."

Stephanie Cole was into funerary things in an irritating documentary called Grave Matters (R2). Claire Rayner, R2's expert-on-everything, was there to enforce cheery briskness but there was no escaping these gloomy facts: crematorium watchdogs inspect the Crimond page in hymn-books for thumbprints (what a job, seeking out the creme de la crem); most people want ashes put in mini-coffins on the mantlepiece; there's a Diana-led trend towards scenic woodland burial sites; you can visit virtual graves on a Web gravesite and - this is so awful I just have to share it with you - easily the most popular secular funeral music is "My Way".

The idea was probably to de-mystify funerals and liberate listeners to bury Grandpa in the garden in cardboard accompanied by Frank Sinatra, but it had the opposite effect on me. The whole thing was, anyway, pre- empted by a recent and far more useful Face The Facts which warned against rogue undertakers out to wrest every last penny from the bereaved.

Finally back to St Francis, whose grave was undisturbed by last September's earthquakes, though the roof of the basilica above it collapsed. In Assisi, 125,000 people are In God's Hands (R4), living in makeshift shelters and hoping for government help. Louise Fryer's investigation emphasised the scale of the disaster, concentrating on the damage done to that famous basilica and, in particular, to Giotto's frescoes.

An art-historian spoke eloquently of Giotto's experiments with space, perspective and portraiture as a refutation of the life-denying heresy of the Cathars. Amongst millions of tiny dusty fragments, a restorer tried patiently to re-create the frescoes just as they were, but the proqramme ended with Dante's view that art, like fame, may not be destined to last forever. Especially in earthquake country.