Phos Hilaron (Hail Gladdening Light)...

Hail Gladdening Light
Of His pure glory poured
Who is the Immortal Father, Heavenly Blest
Holiest Of Holies, Jesus Christ our Lord

Now we are come to the sun's hour of rest
The lights of evening 'round us shine
We hymn the Father, Son and Holy Spirit Divine

Worthiest art Thou, at all times to be sung
With undefiled tongue
Son of our God, Giver of life alone
Therefore, in all the world Thy glories Lord
Thine own

"As early as the 4th Century, Phos Hilaron (Hail Gladdening Light) was already considered ancient, being a mainstay of evening prayers in a tradition known as the lighting of the lamps. At that time in Jerusalem, a candle was kept perpetually burning in the empty tomb of Christ, its glow a symbol of the living light of Jesus. As Christians gathered to worship, the candle was brought forth from the tomb, it's bright, solitary flame calling the church to celebrate the Risen Lord. Phos Hilaron literally means 'hilarious light,' especially meaningful given that this hymn was probably sung in the catacombs by the earliest Church."

--from the Passion "Hymns" CD

*At the latest Passion concerts they do something similar to the lighting of the lamps while this hymn is read by the entire congregation. It's pretty incredible!