1. The essence of mathematics lies in its freedom. ——Kang_er.

2. Mathematics has made an important contribution to the observation of nature. It explains the simple primitive elements in the regular structure, and the celestial bodies are built with these primitive elements. ——Kepler.

3. Mathematical methods penetrate and dominate all theoretical branches of natural science. It has increasingly become the primary measure of scientific achievement. ——Von Neumann.

4. Mathematicians are essentially obsessed. Without them, there would be no mathematics. - Nuvales.

5. When mathematicians derive equations and formulas, they get full happiness like seeing statues, beautiful scenery, hearing beautiful tunes, etc. ——Kopnin.

6. No question can touch people's emotions as deeply as infinity. Few other concepts can stimulate the intellect to produce fruitful thoughts like infinity. However, no other concept can. Like infinity needs to be elucidated. ——Hilbert.