"Yes, alas! through him the Enemy has learned that the One has been found again. He knows where Isildur fell. He knows where Gollum found his ring. He know that it is a Great Ring, for it gave long life. He knows that it is not one of the Three, for they have never been lost, and they endure no evil. He knows that it is not one of the Seven, or the Nine, for they are accounted for. He knows that it is the One. And he has at last heard, I think, of hobbits and the Shire.
"The Shire- he may be seeking for it now, if he has not already found out where it lies. Indeed, Frodo, I fear that he may even think that the long-unnoticed name of Baggins has become important."
"But this is terrible!" cried Frodo. "Far worse than the worst that I imagined from your hints and warnings. O Gandalf, best of friends, what am I to do? For now I am really afraid. What am I to do? What a pity that Bilbo did not stab that vile creature, when he had a chance!"
"Pity? It was Pity that stayed his hand. Pity, and Mercy: not to strike without need. And he has been well rewarded, Frodo. Be sure that he took so little hurt from the evil, and escaped in the end, because he began his ownership of the Ring so. With Pity."
"I am sorry," said Frodo. "But I am frightened; and I do not feel any pity for Gollum."
"You have not seen him," Gandalf broke in.
"No, and I don't want to," said Frodo. "I can't understand you. Do you mean to say that you, and the Elves, have let him live on after all those horrible deeds? Now at any rate he is as bad as an Orc, and just an enemy. He deserves death."
"Deserves it! I daresay he does. Many that live deserve death. And some that die deserve life. Can you give it to them? Then do not be too eager to deal out death in judgement. For even the very wise cannot see all ends. I have not much hope that Gollum can be cured before he dies, but there is a chance of it. And he is bound up with the fate of the Ring. My heart tells me that he has some part to play yet, for good or ill, before the end; and when that comes, the pity of Bilbo may rule the fate of many- yours not least."
 

-Gandalf to Frodo Baggins