In this article, the author presents his “Theory of Nature” (TN). TN is a revolution in physics. TN is dialectical-materialistic physics and cosmology. Matter is placed at the forefront of physics. Matter is introduced into the bosom of physics as the basic physical quantity (BPQ). Physics has been transferred from foundation of the fundamentally false bourgeois-idealist philosophy (BIP) to the foundation of the only true and scientific philosophy of dialectical materialism. From the point of view of nature, modern physics stands on its “head”. TN turns modern physics from “head to feet”. TN puts modern physics on a material basis. Within the framework of TN, a specific representation of matter in nature is determined. Matter of nature is, first of all, the content, the composition of elementary particles (EPs). Within the framework of TN, the structure of the material Universe and the circulation of matter in nature are determined. Within the framework of the TN, an algorithm for the functioning and evolution of the Universe has been determined. Matter is introduced into the bosom of physics as the basic physical quantity (BPQ) in its qualitative and quantitative definiteness.