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...