Range lights are two lights, separated by some distance both vertically and horzontally, which line up when the viewer is "on the range". They are used by those operating ships to line up on a course which is known to be safe (ie. deep water - no shoals). As the lower light is closer to the viewer than the upper light, one knows intuitively that if the lower light is to the right of the upper light, one is left of the range, and vice versa.
It seems to me that this has some deeper meaning.