" Loneliness, I’ve discovered–I discovered then–is a hard-to-define emotion. It’s the product of unfulfillment, a factor of frustration, and as such it is largely an emotion of negatives; it arises most often not from something that has, but from something that has not happened–a letter that has failed to arrive, a telephone that refuses to ring–and its worst feature is that its causes and its control are not governed by anything that you can do or can hope to do, but depend on the actions of some other. Thus it is that it has nothing to do with setting or with circumstance; it can descend on you anywhere, anytime, and as reasonlessly and as abruptly as a cloud can blot out the summer sun. "

― Robert M. Coates ,