This article, which shows the relationship between the metaphysical principles of natural science and phenomenology, shows precisely how Immanuel Kant, through these principles, contributed to the establishment of the phenomenology of perception. Thus, this article which first shows how Immanuel Kant was able to interpret and understand nature from its metaphysical principles, shows precisely and finally how the phenomenology of perception only became possible through the understanding of its principles. This is why the article then shows how these metaphysical principles of natural science are set up as the condition of possibility of the phenomenology of perception in Husserl and Merleau-Ponty.