2. Copper coins are the most basic coins in the past. After passing through the hands of countless people, it means that they are stained with a lot of yang. Putting them at the gate can play a role in blocking evil spirits. Don't bring all the bad things outside into the house, and keep them out, just like people can cross the brazier when they are unhappy. This is just a common way to ward off evil spirits every day, and there is also the moral of making money into treasure.