Kant’s natural philosophy in the Metaphysical Foundations of Natural Science is heavily influenced by Newton’s Principia. However, a closer look makes it clear that Kant’s project has also been influenced by other thinkers. One of these thinkers is Leonard Euler. His work was of great influence for Kant, not only with regards to his view on space and inertia but on the relation between metaphysics and natural science in general. Even though Euler’s Physics built on Newton’s work, he differs from (...) him in fundamental regards, leading to crucial developments inside classical mechanics. Here I will discuss the influence of Euler on the work of Kant and focus on Euler’s view on the two entangled problems of inertia and space. It will become clear that both Euler and Kant went through a development concerning these fundamental notions. After shortly highlighting the differences between Kant and Newton, I shall go through the development of important parts of Euler’s natural philosophy concerning the above mentioned themes. I intend to demonstrate that he, through his refutation of Wolffianism, became an advocate for the necessity of absolute space but also denied the existence of an internal force of inertia. After that I will show how Kant’s reading of Euler lead to crucial changes of his natural philosophy in particular and his philosophical enterprise in general. I therefore analyze Kant’s revision of his theory of space and inertia in his precritical writings. Building upon that, I will show the influence of these thoughts on his Metaphysical Foundations. (shrink)