Hilary of Poitiers

It is the nature of a light to emit its rays whithersoever it is carried about, and when brought into a house to dispel the darkness of that house. Thus the world, placed beyond the pale of the knowledge of God, was held in the darkness of ignorance, till the light of knowledge was brought to it by the Apostles, and thenceforward the knowledge of God shone bright, and from their small bodies, whithersoever they went about, light is ministered to the darkness.