therefore did naugladur hold a secret council of the dwarves of nogrod , and sought how he might both be avenged upon tinwelint , and sate his yet after long pondering he saw not how he might achieve his purpose save by force , and there was little hope therein , both by reason of the great strength of numbers of the elves of artanor in those days , and of the woven magic of gwenniel that guarded all those regions , so that men of hostile heart were lost and came not to those woods ; nor indeed could any such come thither unaided by treachery from within .