McCullough can take the most seemingly trivial facts and make them sing. In what must have been among his most daunting assignments — an invitation in 1989 to address to a joint session of Congress (an honor usually reserved for American presidents and other heads of state) — McCullough mentions, in his opening remarks, a large clock in the Capitol building made by a man named Simon Willard from the early 19th century who did all of his exacting work, McCullough says, “by hand and by eye.”