 These topics in twentieth-century history create an important reminder for historians and for philosophers: a truthful understanding of inhuman atrocity is deeply important for humanity, and it is difficult to attain. We learn from Judt, Snyder, and Applebaum that there are powerful mechanisms of deception and forgetting that stand in the way of an honest accounting of these periods of the recent human past. Discovering and telling the truth about our past is the highest and most important moral imperative that history conveys.