They're killing each other in cold blood. It makes you think about what being human is. As a student of German, Dickey had previously grappled with the question of what happened in Germany during WWII and why. So he was no stranger to thinking about religious, cultural and political conflicts that seem to defy common sense. You begin to understand why people take particular actions.
People are complex.
The translators have to acquire a certain numbness to the evidence in order to do their jobs according to Dickey. Even so, some examples of brutality are emotionally overwhelming. It's important to establish these facts legally for the sake of history. The translation group faced numerous challenges every day. They pored over army manuals and weapons catalogs.