There are innumerable writing problems in an extended work. One book took a little more than six years. You, the writer, change in six years. The life around you changes. Your family changes. They grow up. They move away. The world is changing. You're also learning more about the subject. By the time you're writing the last chapters of the book, you know much more than you did when you started at the beginning.
David McCulloughIt was a day and age that saw no reason why one could not learn whatever was required - learn vitally anything - by the close study of books.
David McCulloughThe year 1776, celebrated as the birth year of the nation and for the signing of the Declaration of Independence, was for those who carried the fight for independence forward a year of all-too-few victories, of sustained suffering, disease, hunger, desertion, cowardice, disillusionment, defeat, terrible discouragement, and fear, as they would never forget, but also of phenomenal courage and bedrock devotion to country, and that, too they would never forget.
David McCullough