If the form is not the form of the content, then it has no value. ——Marx

Mathematical expression is accurate and concise, logically abstract and universal, and formally flexible. It is an ideal tool for communication in the universe. ——Zhou Haizhong

Courage is a kind of tenacity; precisely because it is a kind of tenacity, we have the ability to self-denial and self-conquer in any form. ——Schopenhauer