If he was to travel three thousand years into the past and release his soul, he would need the book of religious spells. Then he thought of Nimueh and her cave. A new trap would have to be set to keep Nimueh busy. Then if he followed the link into the past, his soul could be set free.
Well come stranger. What is it that you desire. The secret of the book on the stone. Is it yours to give. Yes but it can be used for good or evil. Why should I give it to you? Merlin.
Nimueh or Nimue = scorceress.