Good Hobbit Morning chapter 5 "Riddles in the Dark"

Bilbo's way is soon obstructed by an icy pool in the path, but before he could collect his wits, he is met by Gollum, a dark creature, living down in the pool, who used his luminous eyes to catch fish, and always talked to himself, calling himself "my precious". He thought Bilbo might make a tasty treat, but he didn't want to attack while Bilbo was carrying a weapon. To gain time, he challenges Bilbo to a game of riddles, with very dangerous terms: if Gollum asked a riddle Bilbo could not answer, he would have to allow himself to be eaten.