There is a legend that once, the mathematician O 'Keeled taught a student to learn a theorem. After that, the young man asked O 'Keerid what benefits he could get from his study. Once, O 'Keeled called a slave and said to him, "Give him three Apos. He said he would benefit from what he learned." In ancient Greece, where mathematics was still very philosophical, it was understandable to be despised for exploring the origin of the world and the way of all things and obtaining what "benefits". Just like another story: in a bar in Paris, a girl asked her lover why she was late. The young man said that he was studying a math problem. The girl shook her head and asked, "I really don't understand." What's the use of spending so much time doing math? " The young man looked at her for a long time and then said, "dear, what's the use of love?"

Scattered knowledge composed of experience is obviously not as credible as systematic knowledge, and we have always had more trust in the knowledge system. For example, Newton's mechanical system can accurately calculate the motion of objects, even if it is speculated that the solar eclipse in 1 100 million years is almost not bad; Darwin's theory of evolution, which takes species evolution and natural selection as the core, integrates the whole biological world into an orderly organic system, making us know the relationship between different species.

However, even the classic knowledge system is not enough to carry all our trust all the time, because new experience and new research will adjust and update the old knowledge system, and new theories will replace the old ones. The emergence of Einstein's theory of relativity makes Newton's mechanical system a special case in a wider theory; With the development of genetic theory and the accumulation of fossil evidence, Darwin's idea of gradual change in evolution is challenged. Such cases are full of the whole history of scientific development. From time to time, let's look at those seemingly impeccable knowledge systems with suspicion and be alert to them.

However, when people pursue certainty and reliability, there is still an oasis of peace, that is, mathematics. Mathematics is our most reliable science. Once one thing is proved by mathematics, it is certain. In addition, the new mathematical theory has opened up a new field, which can contain but not deny the existing theories. Mathematics is the only science that the new theory does not overthrow the old theory, which is also a proof that mathematics is trustworthy.