_____The narrator's reverie in the library comes to an end when the music in the drawing-rooms is over and he can join the guests there, but he is sure he can continue in the same meditative frame of mind. He's misaken because "a dramatic turn of events occurred which seemed to raise the gravest of objection to my undertaking."
He enters the drawing-room to discover what appears to him to be a masked ball taking place: "everybody seemed to have put on make-up, in most cases with powdered hair which changed them completely." In other words, time has changed them. The transformation is more than physical: M. d'Argencourt, who has long treated the narrator coldly, has become "another person altogether, as kindly, helpless and inoffensive as the usual Argencourt was contemptuous, hostile and dangerous."
the new, almost unrecognizable d'Argencourt stood there as the revelation of Time, which he rendered partially visible. In the new elements which made up the face and character of M. d'Argencourt one could read a certain tally of years, one could recognize the symbolic form of life not as it appears to us, that is as permanent, but in its reality, in such a shifting atmosphere that by evening the proud nobleman is depicted there in caricature.The experience, the juxtaposition of the people he remembers with what time has made of them, "was like what we used to call an optical viewer, but giving an optical view of years, a view of not one moment, but of one person set in the distorting perspective of Time."
And then the table is turned on him: the Duchesse de Guermantes addresses him as "my oldest friend." A young man calls him "an old Parisian." Another young man, whom he had met when he arrived, leaves a note for him signed, "'your young friend, Létourville.' 'Young friend!' That was how I used to write to people who were thirty years older than myself, like Legrandin." Bloch arrives, and in his mannerisms "I would have recognized the learned weariness of an amiable old man if I had not at the same time recognized my friend standing before me ... and was astonished to notice on his face some of the signs generally thought to be more characteristic of men who are old. Then I understood that this was because he really was old, and that it is out of adolescents who last a sufficient number of years that life makes old men."
Most disturbing to him is the realization that he had "discovered this destructive action of Time at the very moment when I wanted to begin to clarify, to intellectualize within a work of art, realities whose nature was extra-temporal." He persists, however, in thinking of himself as young, and when Gilberte de Saint-Loup suggests that they go to dinner together, he agrees, "So long as you don't think it compromising to dine alone with a young man," which causes the people around him to laugh and him to correct himself, "or rather, with an old man." Still, he thinks to himself, "I had not a single grey hair, my moustache was black. I would like to have been able to ask them what it was that revealed the evidence of this terrible thing."
And now it dawned upon me what old age was -- old age, which of all realities is perhaps the one we continue longest to think of in purely abstract terms, looking at calendars, dating our letters, seeing our friends marry, and then our friends' children, without understanding, whether out of fear or laziness, what it all means, until the day when we see a silhouette we do not recognize, like that of M. d'Argencourt, which makes us realize that we are living in a new world.And he continues to survey the crowd of once-familiar faces -- Legrandin, Ski, etc. -- to note how "Time, the artist, had 'rendered' all these models in such a way that they were still recognizable but they were not likenesses, not because he had flattered them, but because he had aged them." He observes the influence of heredity:
I had seen the vices and the courage of the Guermantes recur in Saint-Loup, as also his own strange and short-lived character defects, and in Swann's case his Semitism. I could see it again in Bloch. He had lost his father some years ago and, when I had written to him then, had not at first been able to reply to me, because in addition to the powerful family feeling that often exists in Jewish families, the idea that his father was a man utterly superior to all others had turned his love for him into worship.And he stumbles on the difficulty of reconciling his long-held image of people with the present reality, "to think of the two people under a single heading," to realize "that they are made of the same material, that the original stuff did not take refuge elsewhere, but through the cunning manipulation of time has become this, that it really is the same material, never having left the one body."