So begins Shirley Jackson's classic The Haunting of Hill House.
Perceptions and appearances cannot be trusted. Hill House looks like it was properly built, “… walls continued upright, bricks met neatly, floors were firm, and doors were sensibly shut ...” but Hill House is not sane.
Because … No live organism can continue for long to exist sanely under conditions of absolute reality.
But … is Hill House alive? Ask whatever walks there. It knows. Whenever it dreamt, the dreams too were not sane. When mad dreams and absolute reality are peculiarly inverted … that's when everywhere becomes Hill House … and everyone who lives there … lives alone. Come daylight they dream with their eyes wide open, and at night they keep their eyes sensibly and tightly shut against the darkness of reality.