  With work such as Whewell’s being typical of Duhem’s intellectual context, when Duhem wrote L’évolution de la mécanique, in 1903, he dismissed the Middle Ages as scientifically sterile. Similarly, Duhem’s history of chemical combination, Le mixte et la combinaison chimique, published in book-form in 1902, had jumped from Aristotle’s concept of mixtio to modern concepts. It was only in 1904, while writing Les origines de la statique that Duhem came across an unusual reference to a then-unknown medieval thinker, Jordanus de Nemore. His pursuit of this reference, and the research to which it led, is widely acknowledged to have created the field of the history of medieval science. Where Duhem’s previous histories had been silent, Les origines de la statique contained a number of chapters on medieval science: one treated Jordanus de Nemore; another treated his followers; a third argued their influence on Leonardo de Vinci. In the second volume, Duhem greatly extended his historical scope. As expected, he covered seventeenth-century statics, but he also returned to the middle ages, spending four chapters on geostatics, including the work of Albert of Saxony in the fourteenth century. Les origines de la statique is thus a transition from Duhem’s early conventional histories to the later work for which he is best known, Etudes sur Léonard de Vinci, and Le Système du monde, in which his thesis of the continuity of late medieval and early modern science is fully displayed.