The extraordinary, larger-than-life collaboration between Diaghilev and the Ballets Russes is the stuff of legend, never out of sight in books, articles, popular sleeve notes and academic footnotes. It is arguably long overdue for extravagant film treatment. Let's not be too po-faced, all the same: Diaghilev was in a manner of speaking an enterprising, catalystic rogue, whose character stretches even that cliché, larger than life. He was a visionary of lofty ambition but equally a real man of the theatre, as able to cajole artists to his projects as he could conjure money to the purse.

The creation of Pulcinella is a perfect instance of this chancey creative chemistry. The conductor Ernest Ansermet referred to the 'Rossini-Derain or Pergolesi-Picasso salads' that the troupe dished up after the Great War - salad being used in a not entirely derogatory manner, just to suggest the deft mixture of mischief and magic involved in concocting a masterpiece from what came to hand...

At the time of Pulcinella, Diaghilev was in tricky financial straits and Stravinsky, with a bundle of wartime pieces awaiting first performances, was in a similar state. Both were on the lookout. It was Massine, their fellow conspirator - how else to put it?! - who had unearthed long lost music by Pergolesi that had prompted the idea of a ballet on Neapolitan commedia dell'arte themes. The idea clicked, having in addition the financial attraction of apparently only requiring the music to be arranged. Stravinsky duly had a look at it: 'I looked and I fell in love.' Which meant that he appropriated, lifted or downright pinched raw material - a creative trait he shared with Picasso - so much so that Stravinsky concocted the story that it had been he that had actually found the old music.

Stravinsky's relish for the music and the possibilities it offered for what he called a disequilibrium of instruments, in the ironic context of the clarity and grace of Pergolesi's language, led him to talk of his ear for it thus: 'A colour only has value in relation to the other colours which are placed next to it. Red has no value in itself. It only acquires it through its proximity to another red or a green, for example. And that is what I have wanted to do in music and what I look for first of all is quality of sound.'

These terms are not only unusually painterly but suspiciously picassoid; I suspect they were lifted by the composer, happy that his friend's own musings matched the way his music was evolving. Their gist is quite in keeping with practices in painting that had established themselves before the war, notably with the Fauves, and which inform Picasso's use throughout his life, of colour as subsidiary to drawing and of colour values as vehicles of draughtsmanship. Thus we shouldn't be surprised to see how Picasso's final sets are based on strong outline — as if he expected Stravinsky to supply quite sufficient colour from the pit.

Nonetheless, this creative counterpoint was enriched by Picasso's uncanny way of juxtaposing cubistic linear values, with their counterpoint of skew perspectives making an immediate impact, and a judicious sensitivity to the pastel chiaroscuro magic of moonlight throughout the piece, for him a relatively rare submission to anything so mundane or dictatorial as natural light. It was all of a piece with the play of masks in the action and the clatter of timbres in the band and many regarded it as the most successful collaboration of all the company's various adventures.

Of course, what we have is the final version: from the start Diaghilev had been wondering whether the sets shouldn't be abstract - then still a novel idea - and had been so dejected by Picasso's first plainly too naturalistic efforts that he threw them to the ground and stamped on them. We shall never know what so displeased Diaghilev, except that those possibly too naturalistic first sketches would surely now fetch millions! That was Diaghilev’s way; as it was for the first night party - to drive off in convoy to an illegal party-den run by an ex-convict, where all were happy to drink themselves silly and bring the historic evening to a close with what has been described as a mattress fight. Trust these characters not to settle for a pillow fight.