The section roughly from page 592 to page 654 elaborates on and ties together most of what has gone before. It’s the most concentrated, the most focused, and the best writing in the book so far. And because I’m not sure where to begin in its tangle, I’ll stick with a small, particular incident: Bloch brings Marcel to a brothel.
Bloch is the acerbic intellectual type, Jewish (but not quick to acknowledge it) and not too well-bred, who introduced Marcel to Bergotte’s writing way back in Combray. He is, vividly and painfully, someone who manipulates people into elevating him into a cynical wise man figure. I’ve met many people like him. They aren’t hard to find.
He pushes Marcel to the brothel with an (unrecorded) torrent of philosophical justification:

It was about this period that Bloch overthrew my conception of the world and opened for me fresh possibilities of happiness (which, as it happened, were to change later on into possibilities of suffering), by assuring me that, contrary to all that I had believed at the time of my walks along the Meseglise way, women never asked for anything better than to make love…So that if I owed to Bloch–for his “good tidings” that happiness and the enjoyment of beauty were not inaccessible things that we have made a meaningless sacrifice in renouncing forever–a debt of gratitude of the same kind as that we owe to an optimistic physician or philosopher who has given us reason to hope for longevity in this world and not to be entirely cut off from it when we shall have passed into another, the houses of assignation which I frequented some years later–by furnishing me with samples of happiness, by allowing me to add to the beauty of women that element which we are powerless to invent, which is something more than a mere summary of former beauties, that present indeed divine, the only one that we cannot bestow upon ourselves, before which all the logical creations of our intellect pale, and which we can seek from reality alone: an individual charm–deserved to be ranked by me with those other benefactors more recent in origin but of comparable utility: namely illustrated editions of the Old Masters, symphony concerts, and guidebooks to historic towns. But the house to which Bloch took me (and which he himself in fact had long ceased to visit) was of too inferior a grade and its personnel too mediocre and too little varied to be able to satisfy my old or to stimulate new curiosities. The mistress of this house knew none of the women with whom one asked her to negotiate, and was always suggesting others whom one did not want. She boasted to me of one in particular, of whom, with a smile full of promise, she would say: “She’s Jewish. How about that?” And with an inane affectation of excitement which she hoped would prove contagious, and which ended in a hoarse gurgle, almost of sensual satisfaction: “Think of that, my boy, a Jewess! Wouldn’t that be thrilling? Rrrr!” (619)

The contrast between the long-winded rhapsodizing (I chopped out a few clauses out of the second sentence just to get it to that length) and the crudeness (hell, campiness) of the brothel itself is ironic, but that is undercut by two factors:
First, the long intervening passage where the aged Marcel looks back on Bloch still having opened his eyes to the possibility of individual beauty (which he supposedly will make good on later) in a woman. I would expect that Bloch himself would present the theory, and the coarseness of what follows would make Bloch out to be a pompous faker, rather than the worldly intellect that he previously embodied. But it’s the older narrator himself who intervenes, discussing feelings that he has not yet had, yet were provoked by the same (undescribed) philosophizing that had at the time caused disappointment. Proust goes out of the way to portray some truth in Bloch’s encouragement. Yet Bloch’s poor taste and poorer recommendation indicates that the truth is not one Bloch held, but one to which he inadvertently pointed Marcel, and which, even then, Marcel didn’t recognize until years later.
The obvious implication of the passage–that Bloch is full of shit in the worst way–isn’t falsified, but we’re granted a look at what the ultimate result of Bloch’s bullshit was, and how, even after Marcel was let down by his attempt at realization guided by Bloch, the idea of what Bloch had told him persisted in his mind and grew until it was something more worthwhile than what Bloch had conceived or intended. Bloch has poor taste and dull senses (terrible crimes to Proust), as well as bad intentions (a less terrible crime), but out of his words, eventually, come some value. Bloch himself, though, has little to do with it.
Second, Marcel sells some of his dead aunt’s furniture to the brothel, and, well:

Had I outraged the dead, I would not have suffered such remorse. I returned no more to visit their new mistress, for they seemed to me to be alive and to be appealing to me, like those apparently inanimate objects in a Persian fairy-tale, in which imprisoned human souls are undergoing martyrdom and pleading for deliverance. (622)

The offense he commits is an inversion of what happens with Bloch. Bloch makes idealized promises that reality can’t keep. Here, memories (his own ideals) are polluted by the recasting of an remembered object in a much lower setting. It suggests, once more, that the brothel is not to be taken straight as a gritty portrayal of the way things are. Instead, it is a base influence that revises and corrupts other, less tangible things, i.e., memories.
The simultaneous presentation of (a) Marcel’s initial reverie in response to Bloch, (b) the utter failure of Bloch’s presentation of reality to live up to it, and (c) the eventual value of Bloch’s words, and (d) Marcel’s betrayal of his memories attached to an object, lays out the basic strategy more explicitly than at any point in Swann’s Way: consubstantiality, conflicting internal representations, the inconstancy of reason and perception, and (especially) endless revision.
[By freakish coincidence, ionarts referenced the exact same passage two days ago. I didn’t read all of it because I haven’t gotten to The Guermantes Way just yet, but it looks good. There’s also a nice piece on Swann’s Botticelli obsession vis a vis Odette, a theme which I’ve completely ignored. (Thank you, Nathalie, for the pointer.)]