OK, I waited three days to give others a fair chance; now here's the answer: It was said by the wizard Psamathos to Roverandom - and who could blame the dog for sputtering when trying to pronounce the wizard's name?!
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'Mercy!' cried Gandalf. 'If the giving of information is to be the cure of your inquisitiveness, I shall spend all the rest of my days in answering you. What more do you want to know?' 'The whole history of Middle-earth..
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