In times of turmoil, anything by David McCullough is good medicine. After the Sept. 11, 2001 terrorist attacks, McCullough鈥檚 biography of John Adams, published the same year, provided a model of grace under pressure. All of McCullough鈥檚 books have something to say about human courage, but 鈥1776,鈥 with its passages about colonial Bostonians facing violence and prevailing, seems as much about today as the morning headlines.