In the long ancient times, humans did not have #mirrors, but they still used the "earth" method to see their own figure, that is, to see their reflection on the calm and clear water. Later, when primitive humans were making stone tools, they discovered that there was a kind of stone called "obsidian" that could be ground to illuminate people. This is the so-called "stone #mirror." With the development of technology, the #mirror has evolved into what it is now.