We are a beacon, set upon a hill, to warn mariners from coming to land. We are a buoy

We are a beacon, set upon a hill, to warn mariners from coming to land. We are a buoy, that marks the channel, for the direction of such as sail in the way of safety; and we are a beacon, to show the false lights, which are exhibited to mislead. We are a mark, to point out the way, from the danger of the two extremes; from shallowford, to shallow buoys, and from shallow buoys, to deeper water