You are the light of the world. A city that is set on a hill cannot be hid.
All Commentaries on Matthew 5:14 Go To Matthew 5
Augustine of Hippo
AD 430
You are the light of the world. In the same way as He said above, the salt of the earth, so now He says, the light of the world. For in the former case that earth is not to be understood which we tread with our bodily feet, but the men who dwell upon the earth, or even the sinners, for the preserving of whom and for the extinguishing of whose corruptions the Lord sent the apostolic salt. And here, by the world must be understood not the heavens and the earth, but the men who are in the world or love the world, for the enlightening of whom the apostles were sent. A city that is set on an hill cannot be hid, i.e. [a city] founded upon great and distinguished righteousness, which is also the meaning of the mountain itself on which our Lord is discoursing.
