[Dr. Eckleburg]

I am reminded that it is the West where the sun sets and where darkness is discerned.

For me the symbolism illustrates that the light increases when it travels westward, as the Sun dawns out of the darkness in the east and moves toward a brighter zenith in the west.

[kosta50]

For me the symbolism illustrates that the light increases when it travels westward, as the Sun dawns out of the darkness in the east and moves toward a brighter zenith in the west

Zenith is as high as it will go (zenbith it's straight up, not west); after zenith it all down hill... :)