The great economist Ludwig von Mises showed that economics can be deduced from the axiom that human beings act: individuals consciously select ends and apply scarce means to achieve them. By examining the logical implications of that undeniable fact, one can come to understand the concepts value, cost, time preference, supply, demand, money, price, profit, interest, and so on. In light of this, it is noteworthy that Mises was also an accomplished historian. And more than that, he was an important historiographer; that is, he was interested in the why and how of history. This theorist who is so identified with the a priori method in economics also believed that a knowledge of history and its methods was indispensable to understanding the world.