The controversy over the true nature of material beings in early modern times has had great influence on the subsequent development of natural science. One of the major discussions of the time was the dispute over the measure of force between the followers of Leibniz and Descartes. Today it is still often seen as a meaningless verbal dispute, since there are no empirical criteria for the mathematical formulation of force as a metaphysical concept. In this paper I argue that these disagreements must be attributed to the metaphysical view of nature. The difference of opinion is not only in the evaluation of nature through mathematics but also in the understanding of the concept of force and thus the deep insight into the metaphysics of nature as a whole. In addition, I argue that Leibniz has a much deeper understanding of nature and its metaphysical basis than the Cartesians do. Thus the controversy is not a meaningless verbal dispute but a metaphysically-based subject worthy of discussion.