Occasionally an accident of research produces a book more engaging than the one the historian originally intended. While sifting through material for his Ph.D. dissertation, which dealt with an entirely different topic, Eisen came across a diary from the Vilna ghetto written by Zelig Kalmanovitch. His tone was sober, but not entirely so. The passage that caught Eisen's eye concerned a playground erected around 1942 and the author's inner conflict...