To me there are two Hitlers: one who existed until the end of the French war; the other begins with the Russian campaign. In the beginning he was genial and pleasant. He would have extraordinary willpower and unheard-of influence on people. The important thing to remember is that the first Hitler, the man who I knew until the end of the French war, had much charm and goodwill. He was always frank. The second Hitler, who existed from the beginning of the Russian campaign until his suicide, was always suspicious, easily upset, and tense. He was distrustful to an extreme degree.

To Leon Goldensohn (24 May 1946) - The Nuremberg Interviews (2004)