From which sources does modern capitalism get the energy for constituting and developing itself? Weber's answer is more readily remembered than Sombart's, which plunged into almost total oblivion. But an examination of the contrast between these two masters of the heroic phase of German Sociology in the 20th century gives precious elements for understanding not only the subject of study but also the power and the limits of the sociological analysis which was proposed from opposed angles by the "hedonist" Sombart and the "ascetic" Max Weber.