The new edition, or at least my new edition of the latest English translation, has the bit between the dashes as 'since it enables us to have no regrets, by assuring us that we have had the best of things, and that the best of things was not up to much'. I love it! Here's the Scott Moncrieff version:

No doubt, all their faces had assumed quite new meanings for me since the manner in which they were to be read had been to some extent indicated to me by their talk, talk to which I could ascribe a value all the greater in that, by questioning them, I could prompt it whenever I chose, could vary it like an experimenter who seeks by corroborative proofs to establish the truth of his theory. And it is, after all, as good a way as any of solving the problem of existence to approach near enough to the things that have appeared to us from a distance to be beautiful and mysterious, to be able to satisfy ourselves that they have neither mystery nor beauty. It is one of the systems of hygiene among which we are at liberty to choose our own, a system which is perhaps not to be recommended too strongly, but it gives us a certain tranquillity with which to spend what remains of life, and also — since it enables us to regref nothing, by assuring us that we have attained to the best, and that the best was nothing out of the common — with which to resign ourselves to death.

I may be able to hunt up a few pictures tomorrow...

Proust gives all the best lines to the painter, Elstir. Here he reflects on his younger day, which he might regret, but doesn't, for reasons explained:

“There is no man,” he began, “however wise, who has not at some period of his youth said things, or lived in a way the consciousness of which is so unpleasant to him in later life that he would gladly, if he could, expunge it from his memory. And yet he ought not entirely to regret it, because he cannot be certain that he has indeed become a wise man — so far as it is possible for any of us to be wise — unless he has passed through all the fatuous or unwholesome incarnations by which that ultimate stage must be preceded. I know that there are young fellows, the sons and grandsons of famous men, whose masters have instilled into them nobility of mind and moral refinement in their schooldays. They have, perhaps, when they look back upon their past lives, nothing to retract; they can, if they choose, publish a signed account of everything they have ever said or done; but they are poor creatures, feeble descendants of doctrinaires, and their wisdom is negative and sterile. We are not provided with wisdom, we must discover it for ourselves, after a journey through the wilderness which no one else can take for us, an effort which no one can spare us, for our wisdom is the point of view from which we come at last to regard the world. The lives that you admire, the attitudes that seem noble to you are not the result of training at home, by a father, or by masters at school, they have sprung from beginnings of a very different order, by reaction from the influence of everything evil or commonplace that prevailed round about them. They represent a struggle and a victory. I can see that the picture of what we once were, in early youth, may not be recognisable and cannot, certainly, be pleasing to contemplate in later life. But we must not deny the truth of it, for it is evidence that we have really lived, that it is in accordance with the laws of life and of the mind that we have, from the common elements of life, of the life of studios, of artistic groups — assuming that one is a painter — extracted something that goes beyond them.”

Never get caught with anchors on your bathing costume, or suffer the wrath of the Baron:

“Sir,” he said, stepping back a pace, and with a glacial air, “you are still young; you should profit by your youth to learn two things; first, to refrain from expressing sentiments that are too natural not to be taken for granted; and secondly not to dash into speech to reply to things that are said to you before you have penetrated their meaning. If you had taken this precaution a moment ago you would have saved yourself the appearance of speaking at cross-purposes like a deaf man, thereby adding a second absurdity to that of having anchors embroidered on your bathing-dress.