From Proust Reader by Jim Everett, August 14, 2011
But perhaps to hear music this intensely requires an altered state of mind. Swann’s barren life had eroded his ability to feel deeply. The little phrase changed that and Proust created some of his most startling metaphors to describe Swann’s new musical faculty.
There was a deep repose, a mysterious refreshment for Swann–whose eyes, although delicate interpreters of painting, whose mind, although an acute observer of manners, must bear for ever the indelible imprint of the barrenness of his life–in feeling himself transformed into a creature estranged from humanity, blinded, deprived of his logical faculty, almost a fantastic unicorn, a chimeaera-like creature conscious of the world through his hearing alone. And since he sought in the little phrase for a meaning to which his intelligence could not descend, with what a strange frenzy of intoxication did he strip bare his innermost soul of the whole armour of reason and make it pass unattended through the dark filter of sound! (I, 336-337)
As though the musicians were not nearly so much playing the little phrase as performing the rites on which it insisted before it would consent to appear, and proceeding to utter the incantations necessary to procure, and to prolong for a few moments, the miracle of its apparition, Swann, who was no more able to see it than if it had belonged to a world of ultra-violet light, and who experienced something like the refreshing sense of a metamorphosis in the momentary blindness with which he was struck as he approached it, Swann felt its presence like that of a protective goddess, a confidante of his love, who, in order to be able to come to him through the crowd and to draw him aside to speak to him, had disguised herself in this sweeping cloak of sound. And as she passed, light, soothing, murmurous as the perfume of a flower, telling him what she had to say, every word of which he closely scanned, regretful to see them fly away so fast, he made involuntarily with his lips the motion of kissing, as it went by him, the harmonious, fleeting form. (I, 494)
Swann's Way Volume I; In Search of Lost Time by Marcel Proust, translated by Moncrieff and Kilmartin, revised by Enright. The Modern Library Edition.
On (a) Saturday evening (in April of 1913) Marcel wrote Antoine Bibesco about the concert he had just attended at the Salle Villiers: "Great emotion this evening. More dead than alive I nonetheless went to a recital hall … to hear the Franck Sonata which I love so much." The piece was Cesar Franck's 1886 Sonata in A major for Piano and Violin, performed by the renowned Romanian violinist Georges Enesco and the French pianist Paul Goldschmidt. Proust had never heard Enesco, and he found his playing "wonderful; the mournful twitterings, the plaintive calls of his violin answered the piano as though from a tree, as though from some mysterious arbour. It made a very great impression." … Years later, when inscribing an original deluxe edition of Swann's Way to a young friend, Jacques de Lacretelle, Proust provided a fairly detailed account of the music that inspired (the fictional composer) Vinteuil's compositions. He mentioned, as one source of inspiration, Franck's sonata, as played by Enesco, where the "piano and the violin moan like two birds calling each other."
From Marcel Proust—A Life, William C. Carter 2000.
Reading Carter's biography of Proust, I came upon this mention of Saint-Saëns's Opus 75 and accessed it on iTunes as both the narrator and Swann go on expansively about "the little phrase" which finds it source here.
Despite "passionate" admiration for Saint-Saëns's work, Proust thought less highly of the composer's accomplishments than did his former pupil (the composer) Reynaldo (Hahn). But the haunting melody of one section of the first movement of Saint-Saëns's Sonata I for Piano and Violin, Opus 75, captivated him. Marcel never tired of hearing it and asked Reynaldo (his lover) to play it for him again and again, referring to it as “the little phrase." In the Search… Swann asks Odette (his lover) to play it for him again and again, "the little phrase," now attributed to Proust's fictional composer Vinteuil.
Marcel Proust, A Life William C. Carter 2000
The Saint-Saëns sonata, is it in a minor key—it feels like it—I'm not sure, but after listening to it, Swann in love I'm not, and of that I'm sure. I did download piano music by Reynaldo Hahn, not being familiar with his work, to give it a listen.
But before we go, here is an excerpt of Proust speaking of the language of music as Swann listens to the Vinteuil sonata containing the little phrase performed at the home of the Marquise de Saint-Euverte's.
At first the piano complained alone, like a bird deserted by its mate; the violin heard and answered it, as from a neighboring tree. It was as at the beginning of the world, as if there were as yet only the two of them on the earth, or rather in this world closed to all the rest, so fashioned by the logic of its creator that in it there should never be any but themselves: the world of this sonata. Was it a bird, was it the soul, as yet not fully formed, of the little phrase, was it a fairy—that being invisibly lamenting, whose plaint the piano heard and tenderly repeated? Its cries were so sudden that the violinist must snatch up his bow and race to catch them as they came. Marvelous bird! The violinist seemed to wish to charm, to tame, to capture it. Already it had passed into his soul, already the little phrase which it evoked shook like a medium's the body of the violinist, "possessed" indeed. Swann knew that the phrase was going to speak to him once again. And his personality was now so divided that the strain of waiting for the imminent moment when he would find himself face to face with it again shook him with one of those sobs which a beautiful line of poetry or a sad piece of news will wring from us, not when we are alone, but when we impart them to friends in whom we see ourselves reflected like a third person whose probable emotion affects them too. It reappeared, but this time to remain poised in the air, and to sport there for a moment only, as though immobile, and shortly to expire. And so Swann lost nothing of the precious time for which it lingered. It was still there, like an iridescent bubble that floats for a while unbroken. As a rainbow whose brightness is fading seems to subside, then soars again and, before it is extinguished, shines forth with greater splendor than it has ever shown; so to the two colours which the little phrase had hitherto allowed to appear it added others now, chords shot with every hue in the prism, and made them sing.
Swann's Way Volume I, 495ff; In Search of Lost Time by Marcel Proust, translated by Moncrief and Kilmartin, revised by Enright. The Modern Library Edition.