ition found strong resistance in Newton's physical system, whose work launched a new way of conceiving the nature of physical theory. Duhem interpreted the appearance of the Newtonian system in this manner, with an emphasis on the opposition he offered to Cartesianism (Duhem 1996 [1893], 46). And the main achievement of this approach was to restore physics to its full value, as far as it restored its full autonomy again. Duhem points out, for example, that the use of the term "attraction" to name the force by which bodies tend toward each other does not imply any compromise with the cause or nature of that force. On the contrary. The force can remain perfectly as a symbol whose physical applicability does not depend on knowing the realities that they intend to represent. In the final comment to Definition 8, Newton's position is clear when he states he uses the term attraction to "any sort of propensity toward a center, considering theses forces not from a physical but only from a mathematical point of view", so that he is not "defining a species or mode of action or a physical cause or reason (...)" (Newton 1999, 408). Newton is not committed to explaining the causes of this force that produces gravity. This can also be seen at the beginning of the passage quoted from the General Scholium, when he admits he did not establish the "cause of gravity". This aspect introduces the Principia's method into the autonomy Duhem understands as one of the most fundamental features of physical theory. In addition, Duhem also emphasizes that in Newton's understanding the theory of gravitation retains its full value whatever the result of the investigation of the cause of that attraction. This is what is presented in the General Scholium itself. Newton states that although he did not establish the cause of gravity, "it is enough that gravity really exists and acts according to the laws that we have se forth and is sufficient to explain all the motion of the heavenly bodies and of our sea" (Newton 1999, 943). Put differently, gr