Newton said in the preface of Principles: "Our research is not in technology but in science, not in human hands, but in the power of nature", "Our research is the mathematical principle of natural theory", "We should try our best to deduce it mathematically within the physical scope" and "all natural phenomena should be attributed to mathematical theorems" It can be seen that Newton's idea is very grand. His fundamental purpose is to establish a new system of natural philosophy (natural theory) with physics and mathematical methods as the content, and to establish a new framework for mechanical explanation of all natural phenomena.