In 1846, shortly after his 24th birthday, Frederick Law Olmsted wrote to a friend, full of dismay about the prospect of finding a purpose in life. “I want to make myself useful to the world—to make happy—to help to advance the condition of Society and hasten the preparation for the Millennium—as well as other things too numerous to mention,” he fretted. “Now, how shall I prepare myself to exercise the greatest and best influence in the situation of life I …