In October 1939, C. S. Lewis delivered a sermon at Oxford’s University Church, later published under the title “Learning in War-Time.” World War II had been under way for just a few weeks, and most people in En­gland were starting to recognize the unprecedented level of mobilization the war effort would require. Even before hostilities officially began, some of Lewis’s Oxford colleagues had wondered whether the university should be temporarily closed “in the event of an international emergency.” Could the work of Oxford and places like it—turning young men of fighting age into philosophers, scholars, and critics—be justified at such…