"There was another reason that made the day of this conference unforgettable for Eichmann. Although he had been doing his best right along to help with the Final Solution, he had still harbored some doubts about "such a bloody solution through violence," and these doubts had now been dispelled. “Here now, during this conference, the most prominent people had spoken, the Popes of the Third Reich." Now he could see with his own eyes and hear with his own ears that not only Hitler, not only Heydrich or the "sphinx" Müller, not just the S.S. or the Party, but the élite of the good old Civil Service were vying and fighting with each other for the honor of taking the lead in these "bloody" matters. "At that moment, I sensed a kind of Pontius Pilate feeling, for I felt free of all guilt." Who was he to judge? Who was he "to have [his] own thoughts in this matter"? Well, he was neither the first nor the last to be ruined by modesty."

"That such remoteness from reality and such thoughtlessness can wreak more havoc than all the evil instincts taken together which, perhaps, are inherent in man-that was, in fact, the lesson one could learn in Jerusalem. But it was a lesson, neither an explanation of the phenomenon nor a theory about it.

Seemingly more complicated, but in reality far simpler than examining the strange interdependence of thoughtlessness and evil, is the question of what kind of crime is actually involved here—a crime, moreover, which all agree is unprecedented." - Page 288

"Let us assume, for the sake of argument, that it was nothing more than misfortune that made you a willing instrument in the organization of mass murder; there still remains the fact that you have carried out, and therefore actively supported, a policy of mass murder. For politics is not like the nursery, in politics obedience and support are the same. And just as you supported and carried out a policy of not wanting to share the earth with the Jewish people and the people of a number of other nation though you and your superiors had any right to determine who should and who should not inhabit the world we find that no one, that is, no member of the human race, can be expected to want to share the earth with you. This is the reason, and the only reason, you must hang." - Page 279

"You [Eichmann] also said that your role in the Final Solution was an accident and that almost anybody could have taken your place, so that potentially almost all Germans are equally guilty. What you meant to say was that where all, or almost all, are guilty, nobody is." Page 278

“Where this intent is absent… where the ability to distinguish between right and wrong is impaired, we feel no crime has been committed. We refuse, and consider as barbaric, the propositions "that a great crime offends nature, so that the very earth cries out for vengeance; that evil violates a natural harmony which only retribution can restore; that a wronged collectivity owes a duty to the moral order to punish the criminal" (Yosal Rogat).” - Hannah Arendt, Eichmann in Jerusalem, Page 277

“The trouble with Eichmann was precisely that so many were like him, and that the many were neither perverted nor sadistic, that they were, and still are, terribly and terrifyingly normal.” page 276

“Himmler hardly ever attempted to justify in ideological terms, and if he did, it was apparently quickly forgotten. What stuck in the minds of these men who had become murderers was simply the notion of being involved in something historic, grandiose, unique ("a great task that occurs once in two thousand years"), which must therefore be difficult to bear.

This was important, because the murderers were not sadists or killers by nature; on the contrary, a systematic effort was made to weed out all those who derived physical pleasure from what they did.”

“Hence the problem was how to overcome not so much their conscience as the animal pity by which all normal men are affected in the presence of physical suffering. The trick used by Himmler--who apparently was rather strongly afflicted with these instinctive reactions himself--was very simple and probably very effective; it consisted in turning these instincts around, as it were, in directing them toward the self. So that instead of saying: What horrible things I did to people!, the murderers would be able to say: What horrible things I had to watch in the pursuance of my duties, how heavily the task weighed upon my shoulders!” ― Hannah Arendt

“But the practice of self-deception had become so common, almost a moral prerequisite for survival, that even now, eighteen years after the collapse of the Nazi regime, when most of the specific content of its lies has been forgotten, it is sometimes difficult not to believe that mendacity has become an integral part of the German national character. During the war, the lie most effective with the whole of the German people was the slogan of "the battle of destiny for the German people"… coined either by Hitler or by Goebbels, which made self-deception easier on three counts: it suggested, first, that the war was no war; second, that it was started by destiny and not by Germany; and, third, that it was a matter of life and death for the Germans, who must annihilate their enemies or be annihilated.”

The last I read which had that effect was Arendt's 'Eichmann in Jerusalem', though it might be argued that it's not philosophy as such, though written by an outstanding thinker. It durably influenced my own writing. One can hardly expect a more exciting result from a book.