At the end of the eighteenth century, natural science awaited the synthesis of its philosophical principles in Kant's transcendental philosophy. It would be difficult to over-estimate the extent to which this synthesis has influenced ideas about the foundations of natural science. For example, theories of knowledge such as empiricism and rationalism, that were respectable in the eighteenth century, came to be regarded as naive and dogmatic, respectively, after Kant. It almost appears that the Berlin Academy had a presentiment of this decline in eighteenth century philosophical thinking, and as a homage to it announced a competition question on the foundation of force for the year 1779, although they probably knew in advance that the competition question would be greeted with derision by many in the world. In any case, the competition gives us a good view of the way in which force was conceptualized in the "République des Lettres", in both ontological and epistemological terms. This competition allows us to gauge how far the change in the experience and understanding of force in mechanics had penetrated to the average scientist and interested scholar. This will complement the picture drawn in Chapters 4 and 5, where the controversies about the principle of least action and the true measure of living force were discussed, and interpreted as a change in the foundation of mechanics and as a first exploration of the structural nature of mechanics, respectively.