During the 70 years between oil magnate John D. Rockefeller, Sr.'s emergence as the richest man in the world (c. 1901) and grandson Nelson A. Rockefeller's service as the first U.S. vice president who was appointed, not elected, to that office (1974-77), the Rockefeller family stood as the very epitome of extraordinary wealth and influence, not rivaled in popular imagination until the emergence of Bill Gates in the 1990s. In at least one measure of wealth, John D., Sr. remains the wealthiest American of all time: Bill Gates may have exceeded him in terms of sheer dollars ($40 billion to Sr.'s $1 billion) and he also dominates an industry—computers. But where John D., Sr. at one time received two and a half percent of the national income, Gates has never received more than a half percent. Proof of the pervasiveness and power of the...