I am a beacon, to warn you from the danger of contracting a beacon to burn. I am a ma

I am a beacon, to warn you from the danger of contracting a beacon to burn. I am a mark set up, to prevent your setting up marks to direct beacons, and to burn them in. I am a buoy, to prevent your burning beacons, to mark out the way, where you may set up beacons to burn. I am a light, to prevent your burning lights, where beacons may be set up, to direct posterity. I am a