“Who are we?” ask Leon Kass, Amy Kass and Diana Schaub at the start of “What So Proudly We Hail,” their anthology of works about the American character. “How do we identify ourselves? … What larger community and ideals are we willing to fight and to sacrifice? … What do we look up to and revere?” they ask.

These are good questions to ask in this week of our national birthday, and of much else besides. On July 4, 1776, the 13 original colonies declared themselves a nation, determined to break free of British control and dominion.