The origin of jigsaw puzzles

Also known as "seven clever pictures" and "wisdom board", it is an intellectual toy circulated by the Han people. It evolved from Yan Ji in the Tang Dynasty. It was originally an indoor game for literati and later evolved into a folk jigsaw puzzle. According to Lu Yiqing's "Cold Land Miscellaneous Knowledge" in Qing Dynasty, there are several pictures of Song and Huang banquets, which are divided into twenty-five styles and become sixty-eight styles. Several pictures of butterflies are very clear, but the system has been modified, and triangles are staggered into hooks, such as butterfly wings. Its formula three, its system six, its dozens of three, its variant, where more than one hundred. Recently, there are seven clever diagrams, the formula is five, the number is seven, and there are more than a thousand kinds of changes. The body is simple and changeable, and the tools of the game are enough to dispel boredom and break the silence, so secular people like it. "Now the jigsaw puzzle is cut into five small Pythagorean shapes by a square and pieced together into various things, such as people, animals and plants, pavilions, cars, boats, bridges and so on. You can play alone or with many people. Some important geometric relations can be clarified by using puzzles, and its principle is the "complementary access principle" in ancient arithmetic.