This evening I attended a brief talk by one of the students in my residence on the particularities of the Orthodox Church. It was an interesting overview and one of the things that caught my attention (because of the photos in his slideshow) was the feature of the clergy wearing black.
Doing a bit of research online afterwards, I found this explanation offered for it:
The color black indicates spiritual poverty – it is historically the easiest and cheapest color to dye fabric with. Moreover, black is a color of mourning and death for the priest, the symbolism is 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 is to remind a priest that he ‘dies to the world’ every day and immerses in eternity. Blackness also symbolizes giving up bright colors and thus giving up what the world brings, its glittering, honors and entertainment. Also, as an Archpriest once pointed out to me, stains are readily visible on black, reminding the priest that he is held to a higher standard. His sins and failings will be more visible and judged harsher, than those of other people. In our very secular world, the wearing of the cassock continues to be a visible sign of belief and of the consecration of one’s life to the service of the Lord and His Church.
There’s also this short clip I found in which an Orthodox priest explains why they dress as they do and the benefits for evangelization and witness:
By wearing black, clergy seek to die to themselves and to the world so as to live for Christ and others.
In a sense, they all wear their mortality on their sleeve as they convey their uniform hope for eternal life.