First of all: people are always understood, and understood best, in terms of their family setting--"knowing" a family socially is a highly significant marker but one only seems to know people within one's own generation and the knowledge of who they are and what they are seems to tail off significantly--just as the Narrator really only "knows" Swann's father through a half remembered story and family joke (M. Swann the elder is remembered for saying "Its a funny thing, now; I very often think of my poor wife, but I cannot think of her for long at a time." This is reduced, in the family phrasebook, to "Often, but a little at a time, like poor old Swann.")
During the Narrator's youth M. Swann the younger is a mysterious stranger who appears during the family's summer vacations in Combray. But the child's ignorance of who Swann is is really only an echo of the adult's ignorance:
"For many years, during the course of which--especially before his marriage--M. Swann the younger came often to see them at Combray, my great-aunt and my grandparents never suspected that he had entirely ceased to live in the society which his family had frequented, and that, under the sort of incognito which the name of Swann gave him among us, they were harbouring--with the complete innocence of a family of respectable innkeepers who have in their midst some celebrated highwayman without knowing it--onef the most distinguished members of the Jockey Club, a particular friend of the Comte de Paris and of the Prince of Wales, and one of the men most sought after in the aristocratic world of the Faubourg Sait-Germain."How is it possible, in a world of such formality where different doors and different bells are used to signal the arrival of people one "knows" from servants who one doesn't know, or strangers who must never be admitted to the house, that the family can welcome someone who they don't really know?
Our utter ignorance of the brilliant social life which Swann led was, of course, due in part to his own reserve and discretion, but also to the fact that middle-class people in those days took what was almost a Hindu view of society, which they held to consist of sharply defined castes, so that everyone at his birth found himself called to that station in life which his parents already occupied, and from which nothing, save the accident of an exceptional career or of a "good" marriage could extract you and translate you to a superior caste M. Swann the elder had been a stockbroker; and so "young Swann" found himself immured for life in a caste whose members' fortunes, as in a category of tax-payers, varied between such and such limits of income.Given that Swann is supposed to be modeled, partially, on Charles Ephrussi, one of the wandering Jews from The Hare With the Amber Eyes and that Proust's family itself was "mixed race" with Proust himself rejecting Judaism for Catholicism this seems like a very funny, almost sidelong, reference to the blindness of French society to its own reality. I recently read The Black Count which makes the same point through mere history: the most French of French writers, Alexandre Dumas, had a father who was half Haitian Slave and half French Marquis and the period of the Revolution was one of incredible tumult and social upheaval not merely for the aristocracy that it brought down but for the men and women who rose up and intermarried with the ruling class, the white race, and into "Frenchness." But just as Dumas's father and his military history and the statue commemorating him was disappeared from French military history and from the Square where the statue was placed so this aspect of French Society is invisible to Proust's family. They know it, but they refuse to know it.
One knew the people with whom his father had associated, and so one knew his own associates, the people with whom he was "in a position to mix." If he knew other people besides, those were youthful acquaintances on whom the old friends of his family, like my relatives, shut their eyes all the more good-naturedly because Swann himself, after he was left an orphan, still came most faithfully to see us; but we would have been ready to wager that the people outside our acquaintance whom Swann knew were of the sort to whom he would not have dared to raise his hat if he had met them while he was walking with us.The Narrator refers to the method of determining a person's place in society as a "social coefficient." Its one of my favorite lines in the book. For such a determinedly dreamy, sensual, writer Proust seems to rely heavily on images of money, numbers, tax-rates and real estate to place his characters on an invisible social map. He says:
Had it been absolutely essential to apply to Swann a social coefficient peculiar to himself, as distinct from all the other sons of other stockbrokers in his father's position, his coefficient would have been rather lower than theirs, because being very simple in his habits, and having always had a craze for "antiques" and pictures, he now lived and amassed his collections in an old house which my grandmother longed to visit but which was situated on the Quai d'Orleans, a neighborhood in which my great-aunt thought it degrading to be quartered." (16-17)