Light.

From the gospel according to St.John:
"In the beginning was the Word, and the Word was with God, and the Word was God. 2 The same was in the beginning with God. 3 All things were made by him: and without him was made nothing that was made. 4 In him was life, and the life was the light of men. 5 And the light shineth in darkness, and the darkness did not comprehend it.
6 There was a man sent from God, whose name was John. 7 This man came for a witness, to give testimony of the light, that all men might believe through him. 8 He was not the light, but was to give testimony of the light. 9 That was the true light, which enlighteneth every man that cometh into this world. 10 He was in the world, and the world was made by him, and the world knew him not. "