This is a biographical book. A man reaches the zenith at forty, the top of the hill. From that time forward he begins to descend. If you have any great undertaking ahead, begin it now. You will never be so capable again. ' Of course this was only a theory of Hay’s, a rule where rules do not apply, where in the end the problem resolves itself into a question of individualities. John Hay did as great work after forty as ever before, so did Mark Twain, and both of them gained in intellectual strength and public honor to the very end. Yet it must have seemed to many who knew him, and to himself, like enough, that Mark Twain at forty had reached the pinnacle of his fame and achievement. His name was on every lip; in whatever environment observation and argument were likely to be pointed with some saying or anecdote attributed, rightly or otherwise, to Mark Twain. 'As Mark Twain says, ' or, 'You know that story of Mark Twain’s, ' were universal and daily commonplaces. It was dazzling, towering fame, not of the best or most enduring kind as yet, but holding somewhere within it the structure of immortality.