Why are all the symbols used by Taoist priests yellow?

In the five elements, yellow represents earth, and in people's character, yellow represents benevolence and righteousness. Yellow also represents Di Wang Zhidao. So when the two meanings add up, Taoism likes to draw symbols with yellow paper.

The symbol is not necessarily yellow. People who know symbols will use five colors of symbol paper, each with its own function. For example, one of the functions of black rune paper is to invite "all spirits", "Shu Ren", "righteous people", "good brothers" (ghosts) and even Yin soldiers.