Here's a vignette, containing an image that has been haunting me for weeks.

It's 1913. We're in Paris. If you were there, in a certain place at a certain time, you might have been attracted by the harsh, discordant sounds seeping out of a studio or apartment. No matter if the windows are closed; these belligerent and cacophonous sounds cannot be contained. Repelled yet drawn, you approach the source. Somebody is playing the piano. The sound is huge, but like nothing you have heard before.

As you peek in, trying to peer though the din, you catch a glimpse: there are in fact two people playing, not one. It sounds like the duet from Hell. Two men are scrunched up, probably uncomfortably, on a piano stool while their hands constantly threaten to collide on a keyboard that doesn't seem big enough to accommodate them, far less the music, the source of the colossal din assaulting the ears.

Unless you were clued up, you would not realise you were witnessing a slice of cultural history in the making. The music was an informal, private playing of the piece that, in late May 1913, would erupt into a musical world that would never be the same again: Stravinsky's The Rite Of Spring.

And if you could peek further into that noisy room, you might look closely at the two friends pounding away together at the keyboard. They don't look it, but they are giants. One is the composer of the piece, Igor Stravinsky. And the other, every bit as much a revolutionary as Stravinsky, is the greatest French composer of the age, Claude Debussy. This is not fictitious: it happened. Can you imagine: these two musical pioneers, in the same room, at the same time, playing together on one piano?

What an image. Oh, to have been a fly on the wall. Could a photograph exist? What's so intriguing is that, in their music, Debussy and Stravinsky might seem antithetical. Debussy, the established, mature composer, was the master of suggestion, the man who could evoke the sultry, warm eroticism of a hot afternoon with a curl of flute tone, a quiver of lust from the soft, heady pulse of a string chord, stimulated further by the caress of a harp arpeggio and the breathing of muted horns. Young Igor, on the other hand, as he was about to demonstrate to the world, was a dab hand with a musical sledgehammer, whose blows would be as unpredictable and abrupt as they were violent and savage.

Polar opposites, yet, by 1913, they knew each other well and were great friends. They met in 1910, just after Stravinsky's first ballet for Diaghilev's Ballets Russes, The Firebird, had gone off like a rocket and hurled the young Russian composer to fame. Debussy did not hang about. He was blown away. He was the first celebrity to congratulate and compliment Stravinsky on his great success; and a real friendship was forged.

By the spring of 1913, Debussy was already familiar with the four-hands piano reduction of The Rite Of Spring. It had been produced by Stravinsky primarily for the Ballets Russes rehearsals and study purposes. Debussy followed the process all the way, including his attendance at rehearsals for the ballet. Whether he attended the scandalous premiere at the Theatre des Champs-Elysees on May 29 I can't say. I rather imagine he might have.

Around that time, however, Debussy began to express reservations about the work and the composer. He described The Rite as "primitive music with every modern convenience". It got worse. By 1916 Debussy was describing Stravinsky as "a spoilt child". Was it just sour grapes from the great French composer? Was it the fact that the iconoclastic Russian's new notoriety had stolen the limelight from Debussy?

By 1918, Debussy was dead from cancer. Stravinsky still had 53 years and major changes of style ahead of him. But the imagery of those two sometime-friends and eternal musical giants playing, just for fun, The Rite Of Spring at one piano will haunt me forever.