Literature or Life by Jorge Semprun
This is a great book. Like Semprun's previous book on World War II, "What a Beautiful Sunday," this one uses his experience in Nazi concentration camps to tell a quite remarkable story (and stories within stories within stories), but also as a jumping-off place for wide-ranging musing about life, and art, and the dependency of each on the other (hence the apt title).
The book circles around the liberation of Buchenwald and the first few weeks afterwards, with extended forays into his experiences there, previous experiences with the French underground as a student at the Sorbonne, and with a lot of discussion of writers and philosophers along the way.
He starts by addressing the question of whether an experience like being in Buchenwald can be truly and fully addressed in literature - he says yes, certainly, given enough skill and commitment by the writer. Finding readers who are capable of comprehending and believing what is written is the problem. I think we have a good writer/reader match here, because I find Semprun to be startling in his clarity, illuminating, riveting and very funny from time to time (a sense of humor and absurdity that obviously served him well, and those that leaned on him for support well, too).
There is a bizarrely funny scene at the opening of the book, for example, when three British soldiers, brand new to the scene in Buchenwald walked up to him, and he was so happy to see them ("I felt more like laughing, gamboling in the woods, running from tree to tree") that he tried to engage them in what was, for him, normal conversation ("Say, I bet you fellas are noticing how quiet it is here - it's the birds! The smell of the crematory has driven them off, so the usual racket you hear in the forest just ain't happening here!") - Meanwhile these soldiers are staring at him in open-mouthed horror, as if he was a talking corpse, some kind of zombie... It takes Semprun a few minutes to figure out what the problem is here, and he decides, on reflection, that their perception is correct - that he and his comrades, the survivors, are a sort of zombie, that they hadn't really avoided death - that death and what he calls "radical evil" were so pervasive in the camp that nobody there survived in the usual sense - and he said that for the rest of his life, much of it as a younger man spent continuing to put himself in danger as a revolutionary fighter of various kinds, he felt an odd sort of invulnerability - an assumption that he would not be killed or even caught because he'd already been there, and somehow been given a pass to return to finish his business here.
One of his extended side trips is a discussion of Heidegger, of whom he says, in part, "Of course, there was a certain fascination - sometimes mixed with irritation - with the philosopher's language. With that abounding obtuseness through which one has to hack one's way, cutting clearings without ever reaching a definitive clarity. A never-ending labor of intellectual decipherment that becomes absorbing through its very incompletion."
It seems clear to me that Semprun used his experience with Heidegger partially as a guide in his own development as a thinker and writer, because, again - he writes with exceptional clarity, and no matter how far afield his musings range, he never loses the thread or the point of a remarkable and essential story in the process.