Why did the old waiter want a "clean, well-lighted" place?

A clean,
well-lighted place holds at bay the "nada" that he perceives in life: "What did
he fear? It was not fear or dread.  It was a noting that he knew too well.  It was all a nothing
and a man was nothing too." "Nothingness" or "nada," which he repeats
over ten times, goes beyond loneliness, consisting of a sense of meaningless in the universe
akin to existential angst--a sense that there is no reason for anything,that there is no purpose
or meaning to life. Loneliness is the immediate cause of this, perhaps, and certainly living in
the "light" would mitigate the discomfort of being in the "dark," where one
in fact can see nothing.