China's Four Great Inventions I took in my class.

Sinan (compass) papermaking, gunpowder and printing. The invention of papermaking: it provided economical and convenient writing materials for human beings and set off a revolution of human writing carrier. China's paper-making time itself is very long. In the Eastern Han Dynasty, in 15 AD, Cai Lun invented Cai Hou's paper. Since then, paper has become a cheap and practical tool, and gradually replaced bamboo slips. The invention of printing greatly promoted the spread of culture. Shortly after papermaking, printing was born, and block printing had entered the Dacheng era in Sui and Tang Dynasties, including overprinting. In Song Dynasty, movable type printing appeared, and life-long movable type printing opened a new era of printing, and the real printing tool was realized. The invention of the compass: the origin of the compass is a mystery. In the early autumn tactical era, the application of the compass in the military field was already very common. The mature technology of using the compass on board in the Three Kingdoms era was certain, and there was no historical record in the chaos of the Five Kingdoms. In the Song Dynasty, it was necessary for ships to use compasses. At that time, the sea lanes from China to Arabia were all made in China. (4) Invention of gunpowder and firearms: The invention of gunpowder originated in the late Sui and early Tang Dynasties, and was discovered by warlocks when they were refining alchemy. At the same time, it was quickly used in the military, and the rocket was the earliest effective firearm. By the Song Dynasty, firearms developed from gunpowder had many kinds and powerful power, and gunpowder had been used in mining since the Tang Dynasty. In the Song Dynasty, gunpowder had become a necessary substance for mining. By the Ming Dynasty, black powder and firearms had reached a super peak. After the Qing Dynasty entered the customs, China civilization completely disappeared, and gunpowder became the worst kind. Firearms became toys and jokes. The invention and use of gunpowder symbolizes the use of tools by human beings, which is a milestone progress for human beings from the era of mechanical physics to the era of chemical physics. At the same time, ignorant human beings will use powerful firearms to create many inhuman tragedies and extinctions.