Theodore Roosevelt is of singular interest, because he was, in many evident ways, a self-created figure. He transformed his life into performance art. He intended his life to be an example for others to learn from or even emulate.

I would suggest two approaches to begin the leadership journey in earnest. First would be to ask oneself, in every interaction with others over the course of a single day: How can you best serve this person? Another approach would be to attempt, over the course of a single day, to reframe your declarative statements into questions. The thoughtful use of questions can be transformational. In my experience, most people find these exercises more challenging - and more rewarding - than they would have imagined.

Curiously, for all the outpourings of scholarship on Theodore Roosevelt, no one had written a book focused directly on his leadership approach, working in large part from his own letters and other writings. That opportunity was open, and I was privileged to step in.

Ronald Reagan's career was so unusual, so unprecedented, that this would be very interesting to learn, to gain understanding of his way of looking at the world.

One wonders if Lyndon Johnson and Richard Nixon's administrations may come to be viewed, in the future, as having been underestimated in some respects. To be sure, each ended in failure. Nonetheless, Johnson's accomplishments in civil rights and immigration legislation, and Nixon's in respect to relations with China, may loom larger with the passage of time.

Ronald Reagan was a traditionalist - who purposefully, effectively unleashed innovation and change in himself, in the nation, and in the world. He was a "great communicator" who achieved memorable intimacy with the people everywhere - yet he was often disengaged from his own family.

William McKinley has surely been underrated - in no small part because he was succeeded by a memorable leader, Theodore Roosevelt.