This article examines the relationship between metaphysics and physics, taking as its starting point a provocative question posed by Immanuel Kant in the preface to the Groundwork of the Metaphysics of Morals. Kant suggests a strict distinction between the empirical and rational components of science and calls for a metaphysics of nature that would precede empirical physics itself. However, rather than focusing on a historical interpretation of Kant's philosophy, this text utilizes his reflection as a basis for a more general inquiry. The main objective is to explore what a 'metaphysics of nature' can and must address in contrast to the empirical natural sciences. The work seeks to identify the boundary between knowledge acquired through empirical observation and the a priori foundations of our understanding of the world. Emphasis is placed on how this distinction can be understood in a contemporary context, perhaps under different terminology, to identify areas that escape purely scientific investigation yet remain essential for our grasp of reality.