Duhem regarded the history of physical science as carrying a twofold lesson for the practicing physicist. First, history revealed the slow, groping, yet continuous development of physical theory toward a true description of the relations among natural entities. Second, history also unmasked false explanations and metaphysical beliefs that might seduce the unwary scientist into following an unfruitful line of research. This paper brings forth the central images underlying Duhem's historiographical project and uses the papers by S. Menn and W. A. Wallace to ask what Duhem's enterprise actually meant in practice. I argue that the main question is the following: What is to count as the proper space of historical meaning and explanation? ‘Strong’ Duhemians, such as S. Menn, purchase the longue durée at the cost of making historical agents into completely passive transmitters of conceptual homologies; ‘weak’ Duhemians, such as W. A. Wallace, shorten the temporal distance between agents and permit thereby a modicum of conflict and negotiation within physical theory while still seeking to preserve long-term conceptual genealogies. Both positions, it is argued, allow insufficient room for actors' categories to determine the space of cultural analysis.