Bergotte is the author who cast a spell over young Marcel in the Combray section, and via Swann, he is now able to meet him. It comes at such a crucial point in the book, when Marcel is undergoing feverish revision of what had gone before, that Bergotte’s dialogue with him almost solely redeems the possibility of writing, after Marcel had become disgusted with it earlier.
It is not altogether a positive portrayal: Bergotte is an intellectual visionary possessed of a singular vision, even a genius, but he is myopic. He doesn’t quite have clay feet, but one of the overriding themes of Marcel’s interactions with him (roughly pages 592-618, maybe my favorite sequence so far) is how he moves from being Marcel’s idol of earlier years to a incisive, cranky man very different from the image that Marcel had as a youth. More specifically, the earlier image of Bergotte was not that of a person, but of an ideal, the author of words in which he had seen himself perfectly reflected, when in fact what he was seeing was himself in a mirror he had constructed partially out of Bergotte’s words, but which was mostly a projection of his own mind.
I think that for anyone who develops a particular affection for reading in their early teenage years, there is that set of authors which seem directly in tune with our thoughts. They appear to express inner truths that were previously thought unshared by anyone. These authors usually disappoint us later when it turns out that they were aiming at something else entirely, and somewhere in college, we figure out that we have to be a lot more careful before verbal intoxication leads to overly zealous identifying of kindred spirits. After that, those authors go into a very special category where we neither criticize them nor praise them, since we know we’ll be talking more about ourselves than about the authors. And there’s a little bit of resentment to the authors for tricking us so badly, when we were so vulnerable. I’m not yet ready to divulge who’s on my version of that special list.
Bergotte does not disappoint Marcel in such a severe way, though he is acutely aware of the gap between the man he meets and the author he read:

I had told him [Bergotte] everything that I felt with a freedom which had astonished me and which was due to the fact that, having acquired with him, years before (in the course of all those hours of solitary reading, in which he was to me merely the better part of myself), the habit of sincerity, of frankness, of confidence, I found him less intimidating than a person with whom I was very uneasy about the impression that I must have been making on him, the contempt that I had supposed he would feel for my ideas dating not from that afternoon but from the already distant time in which I had begun to read his books in our garden at Combray. (611)

And so he tells Bergotte, after Bergotte remarks on how precocious he is in appreciating the “pleasures of the mind”:

I felt how purely material was everything that I desired in life, and how easily I could dispense with the intellect. As I made no distinction among my pleasures between those that came to me from different sources, of varying depth and permanence, I thought, when the moment came to answer him, that I should have liked an existence in which I was on intimate terms with the Duchesse de Guermantes and often came across , as in the old toll-house in the Champs-Elysees, a fusty coolness that would remind me of Combray. And in this ideal existence which I dared not confide to him, the pleasures of the mind found no place. (613)

Bergotte finds this surprising, and though Marcel is disappointed, he is still encouraged that such discussions can take place, and that the dead image of literature pushed on him by the staid M. de Norpois (around page 488 or so) earlier is not the limits of writing as practiced. Bergotte, not the man (or spirit) that Marcel had imagined, is still able to bring about a meaningful dialogue. Of course, just to emphasize the gap, Bergotte then trashes Cottard and Swann, which hits Marcel like an earthquake:

“[Swann’s] typical of the man who has married a whore, and has to pocket a dozen insults a day from women who refuse to meet his wife or men who have slept with her. Just look, one day when you’re there, at the way he lifts his eyebrows when he comes in, to see who’s in the room.” (615)

But what about Bergotte himself? Though initially appearing aloof, like the locked container of infinite knowledge, he shortly comes off as judgmental, amoral (in how he treats those around him), and petty. (More so than Swann)
His singular, unique vision, as described, should be a tip-off that he’ll eventually be painted as limited by that singularity of his vision. In Proust, strength and depth of feeling in a single direction invariably reveals a corresponding deficit in other directions. The judgment comes down most harshly when Proust pulls back to describe Bergotte’s later years:

[Bergotte] would say also, with a shy smile, of pages of his own for which someone had expressed admiration: “I think it’s more or less true, more or less accurate; it may be of some value perhaps,” but he would say this simply from modesty, as a woman to whom one has said that her dress or his daughter is beautiful replies, “It’s comfortable,” or “She’s a good girl.” But the instinct of the maker, the builder, was too deeply implanted in Bergotte for him not to be aware that the sole proof that he had built both usefully and truthfully lay in the pleasure that his work had given, to himself first of all and afterwards to his readers. Only, many years later, when he no longer had any talent, whenever he wrote anything with which he was not satisfied, in order not to have to suppress it, as he ought to have done, in order to be able to publish it, he would repeat, but to himself this time: “After all, it’s more or less accurate, it must be of some value to my country.” So that the phrase murmured long ago among his admirers by the crafty voice of modesty came in the end to be whispered in the secrecy of his heart by the uneasy tongue of pride. And the same words which had served Bergotte as a superfluous excuse for the excellence of his early works became as it were an ineffective consolation to him for the mediocrity of the last. (599)

This is such a sneaky technique, and Proust loves it. (He did the same with Swann, and there are frequently other references to the futures of other characters.) To pull back drastically and look at Bergotte years later, a self-deluding shadow of his former genius, pulls the rug out from any authority Bergotte once had. Whatever follows from Bergotte–and what follows does have a profound effect on the young Marcel–has its authority weakened. It is only a variant of Proust’s techniques elsewhere, where he destabilizes authoritative words and thoughts by revising them, but this nearly seems cheap. What redeems it is the idea that the same words, and indeed the same thoughts, could be used by a single man at different points in his life and carry completely different implications: at one time false modesty over one’s genius, at a later time a sad excuse. It makes the later Bergotte, whom we haven’t met yet, explicable and sympathetic in the terms of his current self.
For comparison, Robert Musil’s The Man Without Qualities deals heavily in the irony that the great plans of his Austrian political figures in 1912 will come to nothing when the war breaks out, but he only refers to it sparingly. The only reference that comes to me offhand, in fact, is almost in passing. I’ll quote the passage, if only to illustrate how differently Musil deploys his judgments (and also because I like it so much):

Had Arnheim been able to see only a few years into the future, he would have seen that 1,920 years of Christian morality, millions of dead men in the wake of a shattering war, and a whole German forest of poetry rustling in homage to the modesty of Women could not hold back the day when women’s skirts and hair began to grow shorter and the young girls of Europe slipped off eons of taboos to emerge for a while naked, like peeled bananas. He would have seen other changes as well, which he would hardly have believed possible, nor does it matter which of those would last and which would disappear, if we consider what vast and probably wasted efforts would have been needed to effect such revolutions in the way people lived by the slow, responsible, evolutionary road traveled by philosophers, painters, and poets, instead of tailors, fashion, and chance; it enables us to judge just how much creative energy is generated by the surface of things, compared with the barren conceit of the brain. (443)

Is it just me, or is there actually a bit of overlap here in their concerns, if not their tones? It reads like a defense of Marcel’s lack of interest in Bergotte’s “pleasures of the mind.” Now, Musil truly isn’t interested in the surfaces he references, while Proust makes them the center of the novel. If Proust does have an affiliation with one of the German writers of that era, it’s Mann, who I’ll get to next time.