In 500 BC, Hippocrates, a disciple of the Pythagorean school in ancient Greece, discovered an amazing fact: the diagonal of a square and the length of one side are incommensurable (if the side length of a square is 1). The length of the diagonal is not a rational number), which is quite different from the philosophy of "everything is a number" (only rational numbers) of the main Sect. This discovery surprised and angered the leaders of this school, thinking that it would shake their dominant position in academia. Therefore, the Hebrews were imprisoned, tortured in various ways, and finally sentenced to shipwreck death.

The discovery of Bishop's disciples revealed the defects of rational number for the first time, which proved that it could not be treated equally with a continuous infinite line. Rational numbers are not covered by points on the number axis, and there is a "gap" on the number axis that cannot be expressed by rational numbers. And this "gap" has been proved to be "countless" by later generations. Thus, the assumption that the ancient Greeks regarded rational numbers as a continuous "arithmetic continuum" was completely shattered. The discovery of incommensurability, together with the famous Zeno paradox, is called the first crisis in the history of mathematics, which has had a far-reaching impact on the development of mathematics for more than two thousand years, prompting people to rely on proof instead of intuition and experience, promoting the development of axiomatic geometry and logic, and gestating the bud of calculus.

What is the essence of incommensurability? There have been different opinions for a long time, and there is no correct explanation. The ratio of two incommensurable degrees has always been considered unreasonable. /kloc-Leonardo da Vinci, a famous Italian painter in the 0/5th century, called it an "irrational number", and Kepler, a German astronomer in the 0/7th century, called it an "indescribable number".

However, truth cannot be submerged after all. It is "unreasonable" for the bishop's school to obliterate the truth. People named this incommensurable quantity "irrational number" to commemorate the Hebrew who died for the truth-this is the origin of irrational number.