Klemperer's book, his journal account of his life in Germany as an assimilated Jew from 1933 to 1945, is one of the most important first-person accounts of life in Nazi Germany from a Jewish perspective. It is an extremely important text because he is one of the few Jewish witnesses of the entire Nazi period. (Most Jews either left Germany or were exterminated.)

Klemperer survived because he was married to an Aryan wife. He hoped, early on, that his service fighting in World War I would protect him. He also hoped being a convert to Christianity would matter, and he joined the Confessing Church, which tried to offer some protection to converted Jews expelled from Hitler's German Church. Here too, Klemperer was unsuccessful: being a Christian could not rub away the "stain" of Judaism in Nazi Germany any more than being a Christian could save a black from slavery in the pre-Civil War South in the United States. Judaism was defined by the Nazis as a race, not a religion.

Klemperer's diaries have added importance because they are written by an intelligent, insightful person, a professor of Romance languages forced from his university position because of his ethnicity. Klemperer had an ear for the nuances of language and records Nazi rhetoric with disgust, such as the emphasis on spectacle and the bragging about the invasion of Russia as the "biggest" invasion of all time, as if it were a Barnum and Bailey circus event and not a war.

But primarily, the diaries are an ongoing account of the gradual deterioration of Jewish life under Nazi rule. Klemperer lives with a noose around his neck that slowly grows tighter and tighter—and about which, stripped of citizenship and rights, he can do nothing. He often expresses hopelessness and anger, wishing at one point that a former colleague, who now shuns him, be hanged from the tallest lamppost. But mostly, he simply wants to survive.

One of the more poignant and detailed accounts is of his eight days in a Nazi prison for failing to properly install a blackout shade during World War II—a "crime," as he notes, that would have gotten an Aryan at most a fine for the first offense. A great fan of movies, he notes all the jail scenes he has seen in American gangster films—then comments on what he calls a "banal" truth, that you can't begin to understand the torment of an experience until it happens to you. We could say the same of our reading of his journals, even though they do provide us with a powerful and memorable glimpse of what he endured.

He was scheduled for deportation to a concentration camp when, ironically, he and his wife were saved by the U.S. fire bombing of Dresden. Given the catastrophe, the Nazis relaxed the rules about identification papers, and the fleeing Klemperer was able to leave the city as an Aryan and survive the war.