Chronochromie was the second of Messiaen's commissions from Heinrich Strobel, director of the Donaueschingen Festival for which Réveil des oiseaux (1953) had also been composed. Strobel insisted there should be no piano or ondes Martenot in the new work, but otherwise gave Messiaen a free hand. The result is a large orchestra notable for its huge arsenal of pitched percussion, including glockenspiel, xylophone, marimba and bells, together with instruments of relative pitch - gongs, cymbals and tam-tam.
Messiaen began work in the summer of 1959, at first planning a 'Postlude' (his initial working title) to the great solo piano cycle Catalogue d'oiseaux which had had its first complete performance earlier in the same year, on 15 April. The eventual title devised by Messiaen merges the Greek words 'Khronos' and Khrôma - 'time' and 'colour' - referring to the interaction between two streams of musical material, the one rhythmical, the other 'sonorous'.
The rhythms of Chronochromie are founded on a 'mode' of 32 different durations, subject to a system of permutations, a technique first used in simpler form in the piano etude Île de feu 2, composed in 1950. These are used either singly or in simultaneously sounded groups of three, and are assigned to metal percussion instruments in such a way as to make their timbres distinct. At the start of Strophe I, for example, one permutation is given to the gongs, another to bells, while the third is divided between cymbals and tam-tam.
The same passage illustrates the two ways in which this rhythmic material is 'coloured'. First, each permutation is shadowed by dense harmonies (in seven or eight parts) played by solo strings - the gongs in tandem with solo 1st violins, the bells with 2nd violins, and the cymbals and tam-tam with violas and cellos. The sound of the string harmonies is arrestingly dry, with an accent to each new chord followed by a sudden pianissimo, played non vibrato, an effect that Messiaen would return to in Sept Haïkaï.
The second type of 'colouring' is provided by the sounds of nature. For the most part these are birdsongs, drawn from the vast collection of notations that Messiaen had made in the French countryside in the 1950s and that had not found their way into the Catalogue d'oiseaux.
Mingled with these are birds from more distant parts of the world: Mexico, Sweden and Japan. Other sounds from nature imitated in Chronochromie come from the mountains around Messiaen's summer home at Petichet in the French Alps. Towards the end of the Introduction, for instance, we hear the rushing of the wind, then stark, heavy chords that stand for rocks, and finally a mountain torrent in spate, the hiss and roar of white water captured in musical notation in the Gorges de la Bourne.
The treatment of birdsong is superbly exhilarating, the full resources of the orchestra used to evoke the timbres Messiaen perceives in the songs and cries of each species. Unlike Réveil des oiseaux or Oiseaux exotiques (1956), the rhythms of the birdsong are no longer confined to regular time signatures; instead, metres are often in a state of flux, articulating the natural stress of the song, and at the same time demanding the utmost virtuosity from the players.
The structure of Chronochromie employs the pattern of Strophe-Antistrophe-Epode found in Greek poetry; traditionally, the Strophe and Antistrophe share form and metre, while the Epode makes a crowning conclusion. Messiaen had used this form once before, in Le Chocard des Alpes, the opening piece of Catalogue d'oiseaux, linked with Chronochromie by its mountain setting.
In Chronochromie the form is expanded to seven sections by the addition of a second Strophe and Antistrophe together with an Introduction and Coda. The difference between the Strophes and Antistrophes is that the former employ the rhythmic permutations throughout, the latter only partially. This affects the style of the 'colouring' birdsongs. In the Strophes these form medleys, with each instrument having its own birdsong; in the Antistrophes the birdsong choruses sing in concert, with pride of place going to the exuberant calls of the song thrush, answered by the skylark in a virtuoso transcription for xylophone and marimba.
The Épôde, the penultimate movement, is an extraordinary polyphony of birdsongs scored for eighteen solo strings. It was this section that most disconcerted audiences at the first performances of Chronochromie. At the Paris première (13 February 1962, at the Théâtre des Champs-Elysées), one senior critic, Rene Dumesnil, likened the reception to the notorious premiere of Le Sacre du printemps, which by coincidence had taken place in the same auditorium nearly half a century earlier.
The storm of criticism drove Messiaen to make a rare public defence of his music: 'My permutations of durations are rigorous, my birdsongs are entirely free. Rigour is implacable, but so too is freedom. Mingling them together shocks audiences of all persuasions. And when in the Épôde a vast counterpoint of birds in eighteen real voices unfolds simultaneously, with all the freedoms tangled, the apparent disorder of inextricable sounds is the last straw for the audience, and provokes shouts and tumult.'
Messiaen ended with a defiant flourish: 'Freedom! Doubtless we're afraid of this word. In the end it is freedom that triumphs in my music. And if I had given a title to this modest defence, perhaps I would have called it: A Plea for Freedom.'