Eastern Orthodox/Priests wearing black
Why do the Orthodox Priests dress in black?
The color black indicates poverty and humility--giving up bright colors and what the world brings; its fashions, honors, and entertainment. Moreover, black is a color of mourning and death. For the Priest, this means symbolically dying to oneself to rise and serve the Lord as well as giving witness of the Kingdom yet to come. Black is associated with sorrow but in the case of priestly robe this color has another symbolic meaning. A black cassock reminds a Priest that he ‘dies to the world’ every day and is immersed in eternity.
Further, the color black is the symbol of authority. A judge sitting in the judgment chamber wears black. In many countries, an advocate who pleads in the court wears a black robe. In the same manner, wearing the black robes during the services is a mark of the spiritual authority of Priests.