The sturdy intelligence so clearly at work in these diaries provokes a reader to admiration—and plunges him into lingering mystery. … It is a genuine conundrum. Speer finally illustrates not evil’s banality, but its centrality, its endless presence in people, its ability to fly like bacteria into the blood cells of the high-minded, breaking down their moral immunities and laying waste to their goodness.

Thomas Mallon, A Book of One's Own, loc. 750