Lucas Engelhardt explains the many contributions of an early precursor to not only the Austrian school but to the whole of economic thought, Juan de Mariana of the 16th century Spanish scholastics. Mariana’s book On the King and the Royal Institution stressed the importance of remembering that kings are under a greater natural moral law and ought to be punished when they violate it. Mariana distinguished between a tyrant and a king by how the ruler viewed the property of his citizens. Regarding the exchange value of money, Mariana understood the value was determined by the supply and demand of money so that debasement of the currency led to rising prices. Engelhardt also explains Mariana’s understanding of subjective valuation. The Who Is? podcast is available on iTunes, Google Play, Stitcher, Soundcloud, and via RSS.