y structure of the world" (Duhem 1892a, 150, 158159 ). However, like Poincaré, Duhem recognizes the importance of the interactions between metaphysics and physics (and their criticism), a recurring subject of his historical work (Leite 2013). Theories are constructed from hypotheses, taken as the starting point of the mathematical deduction, and they do not have to be a mere translation of experimental laws. Like Poincaré, Duhem distinguishes between phenomenological theories and (mechanical) theories that postulate unobservable entities. Both value mathematical physics and its tool: mathematics. Mathematical analysis, Duhem writes, is "a necessary instrument for the construction of any physical theory (...) and the physicist must be able to use, if necessary, all the parts of this instrument". At the same time mathematical analysis deserves to be cultivated by itself because of its beauty, and because sometimes its internal improvements end up rendering service in other fields of physics (Duhem 1892a, 171-173).19 The points of convergence between Duhem and Poincaré are quite numerous, since more than half of the "Quelques réflections (...)" illustrate this agreement (Duhem 1892a, 139-165). Duhem differs from Poincaré only in his appreciation of the various methodologies or styles of making theory (Duhem 1893; see Maiocchi 1992, 377-380); and he makes judgments that reflect his ideal of a more phenomenological theory 19 This is another resonance; Poincaré will say: "Mathematics have a triple goal. They must provide an instrument for the study of Nature. But that is not all, they have a philosophical aim, and, I dare say, an aesthetic aim" (Poincaré 1897, 857). João Príncipe – Poincaré and Duhem: Resonances in their First Epistemological Reflections 153 and his constant concern for global coherence and uniqueness of representation.20 Although the comparison given in this article is limited to the early 1890s, let us point out some factors of the progressive separation of Duhem and Poincaré.21 In the f