Ron Paul alludes to this speech in his book End the Fed (pp. 51-52):
Mises, at the time, was elderly but sharp. His subject was socialism, and his lecture explained why socialism always fails due to the absence of a free market pricing structure for capital goods... The lecture was held in a modest-sized classroom, but the place was overflowing. Popularizing Austrian economics at the time was in its very early stages, but it was obvious even then that there was a starvation for truth in economics.
Ludwig von Mises was the acknowledged leader of the Austrian school of economic thought, a prodigious originator in economic theory, and a prolific author. Mises's writings and lectures encompassed economic theory, history, epistemology, government, and political philosophy. His contributions to economic theory include important clarifications on the quantity theory of money, the theory of the trade cycle, the integration of monetary theory with economic theory in general, and a demonstration that socialism must fail because it cannot solve the problem of economic calculation. Mises was the first scholar to recognize that economics is part of a larger science in human action, a science that he called praxeology.