Ernst Mach (1838–1916) was, no doubt, one of the most prominent scientists of the late nineteenth and early twentieth centuries. Mach, a physicist and philosopher, was a pioneer for an integrated history and philosophy of science and had a major influence on the origins and evolution of Logical Empiricism and Vienna Circle. Mach had also a major influence on the methodological development of various sciences. His doctrine of elements, historical-critical method and the principle of economy (also economy of thought, thought economy) played a crucial role in diverse scientific fields. Interpreting Mach focuses on Mach’s epistemological and methodological ideas.