What Do the Eyes of Dr. T.J. Eckleburg Symbolize?

The billboard of Dr. Eckleburg figures in passing in the early part of the novel. It was mentioned to be watching over the garage of the Myrtle and her husband, George Wilson. Later in the novel, George made reference to the billboard when he accused Myrtle of having an affair with Tom Buchanan, saying that God sees everything. Finally, the billboard was in the backdrop in the pivotal part of the novel when Daisy, who is Tom's wife, hit Myrtle with a car, killing her.