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
Theophylact of Ochrid
AD 1107
First He calls them salt and then light. He who reproves what is done in secret is light, "for whatsoever doth make manifest is light" (Eph. 5:13) The apostles did not enlighten one nation only, but the world.
He teaches them to struggle and to be strict in living a virtuous life, for they will be in view of all. Do not imagine, He says, that you will be hidden away in some corner, for you will be most visible. See to it, then, that you live blamelessly, lest you become a stumbling block for others.