Lilith

Lilith by George MacDonald. Lilith is a fantasy novel written by Scottish writer George MacDonald and first published in 1895. Mr. Vane, the protagonist of Lilith, owns a library that seems to be haunted by the former librarian, who looks much like a raven from the brief glimpses he catches of the wraith. After finally encountering the supposed ghost, the mysterious Mr. Raven, Vane learns that Raven had known his father
indeed, Vane's father had visited the strange parallel universe from which Raven comes and goes and now resides therein. Vane follows Raven into the world through a mirror (this symbolistic realm is described as "the region of the seven dimensions," a term taken from Jacob Boehme). Inside the world, Vane learns of a house of beds where the dreamers sleep until the end of the world in death: a good death, in which life is found. Vane's grandfather refused to sleep there and is, instead, forced to do battle with skeletons in a haunted wood. After a treacherous journey through a valley (where the moon is the only thing to keep him safe), Mr. Vane meets the Little Ones, children who never grow up, remaining pure children or becoming selfish and getting bigger and dumber, turning into "bags" or bad giants.