Consider the Second World War. In the periods before, during and after this tragic event, there were acts of great courage and great cowardice. People died nobly and did ignoble things in order to survive. Entire cultures were ripped up and torn to shreds. Cities and towns were flattened, people were terrorised, and many fought back, forfeiting their lives so that others could live free from oppression. In the Second World War, the cruel were given the chance to shine and the brave were forced to hide, to flee, to stow themselves away, and to act.
If we wish to learn the truth of human nature, the ugly and the beautiful, we should study the most terrible of times. Because only in these most extreme situations is the full spectrum of humanity revealed.