In the book, The Zookeeper's Wife, author Diane Ackerman describes the brutal occupation of Warsaw, Poland by the Nazis. The Warsaw Zoo became a hiding place for members of the Resistance and Jewish refugees.

Keeping one person alive often required putting a great many in jeopardy. It tested them nonstop as they resisted both propaganda and death threats. Yet 70,000-90,000 people in Warsaw, or about one-twelfth of the city's population, risked their lives to help neighbors escape. Besides the rescuers and Underground helpers, there were maids, postmen, milkmen, and many others who didn't inquire about extra faces or extra mouths to feed.

Possible Preaching Angle:

Many working together, doing even a little, can do much to conquer evil.