'When did I first begin to guess?' he mused, searching back in memory. 'Let me see - it was in the year that the White Council drove the dark power from Mirkwood, just before the Battle of Five Armies, that Bilbo found his ring. A shadow fell on my heart then, though I did not know yet what I feared. I wondered often how Gollum came by a Great Ring, as plainly it was - that at least was clear from the first. Then I heard Bilbo's strange story of how he had "won" it, and I could not believe it. When I at last got the truth out of him, I saw at once that he had been trying to put his claim to the ring beyond doubt. Much like Gollum with his "birthday present". The lies were too much alike for my comfort. Clearly the ring had an unwholesome power that set to work on its keeper at once. That was the first real warning I had that all was not well. I told Bilbo often that such rings were better left unused; but he resented it, and soon got angry. There was little else that I could do. I could not take it from him without doing greater harm...'