Titan: The Life of John D. Rockefeller, Sr. by Ron Chernow. Between 1870 and 1900, John Rockefeller drove the price of oil down 80 percent, democratizing first the most important illuminant and then the most important propellant since fire. In the process, he became the richest man in the world – supplanting Andrew Carnegie, who during the same period drove down the price of a steel rail by 70 percent. (American GDP per capita soared by two thirds in those 30 years as a direct result of both men’s efforts.) Chernow is our era’s finest biographer; in Titan he virtually throws in a perceptive study of Rockefeller junior, perhaps America’s greatest philanthropist.