What leads up to Klemperer's change in purpose and tone in his diary, I Will Bear Witness: A Diary of the Nazi Years, 1933-1941?
Klemperer began incorporating a record of the effects of Hitler's regime into his life-long habit of diary writing from the beginning of Hitler's entrance to power. Klemperer noted the changes that first began to appear at the edges of life, the small things. His record starts with the ways in which Jews were first forbidden to use telephones or keep pets and expands as the restrictions expanded to being unable to buy eggs, meat, vegetable, or bread. He records the added impact made by the yellow Jewish Star of David--which all Jews were forced to wear--into these daily encroachments into Jewish humanity and life. Not only were Jews not allowed to buy food or take a walk in the park, they were very publicly not allowed to these things.
Klemperer wrote his diary at great personal peril. It was a crime to keep a diary under Hitler's rule. Klemperer's home was repeatedly raided and destructive searches repeatedly made. Had it been found, the sentence for the crime would have been execution. As time went on and the Hitler regime went from horrible to increasingly atrocious, Klemperer realized his diaries were part of a greater purpose, a chronicle of an event larger than his local experience. He wrote: "This is my heroics. I want to bear witness, precise witness, until the very end." It is when he saw this grand scale that the purpose and tone of his diary inevitably underwent a change.