July 31 marks the 93rd birthday of the world's foremost living economist, Milton Friedman. Winner of the Nobel Prize for Economic Science, the Presidential Medal of Freedom, and the National Medal of Science, Friedman advances the principles of individual choice by popularizing ideas that include school vouchers and private retirement accounts. Through essays, speeches, and books such as Capitalism and Freedom, and Free to Choose, Friedman champions the ideas of liberty. "Milton Friedman has done more than defend freedom as an abstract ideal," President George W. Bush recently said, "He has creatively applied the power of freedom to the...