Daylight does not lend itself to terror: objects and people are plain to see; and we encounter there only those things which dare to show themselves in the glare of day. But night, opaque night denser than walls, night, empty and infinite and so black and fathomless that terrifying things reach out and touch us, night when we feel horror stirring, mysteriously prowling―night seemed to him to hide some unknown, imminent, threatening danger. What could it be?