“To measure is to determine the ratio of one quantity to another which is invariable or assumed to be invariable. Invariability in respect of the property to be measured, or at least the legitimacy of assuming such invariability, is a sine qua non of all measurement. Only when this assumption is admissible is it possible to determine the variations that are to be measured.”

Austrian and American political economist and philosopher

Ludwig Heinrich von Mises was an Austrian and American political economist and philosopher of the Austrian school. He is known for his work on classical liberalism and the place of consumers in a market economy. He wrote and lectured widely on the social value of classical liberalism, and on praxeology, the study most closely associated with his work. He is also known for comparing communism and capitalism, and for defending liberal ideas against the spread of illiberalism and authoritarianism in 20th-century Europe.