Until then I had always thought of loneliness as something negative—an absence of company, and, of course, something temporary... That day I had learned that it was much more. It was something which could press and oppress, could distort the ordinary and play tricks with the mind. Something which lurked inimically all around, stretching the nerves and twanging them with alarms, never letting one forget that there was no one to help, no one to care. It showed one as an atom adrift in vastness, and it waited all the time its chance to frighten and frighten horribly—that was what loneliness was really trying to do; and that was what one must never let it do...
John Wyndham, The Day of the Triffids
loneliness