the world was fair , the mountains tall , in elder days before the fall of mighty kings in nargothrond and gondolin , who now beyond the western seas have passed away ... ... and this was to be the crown and completion of the whole : the doom of the noldorin elves in their long struggle against the power of morgoth , and the parts that hurin and turin played in that history ; ending with the tale of earendil , who escaped from the burning ruin of gondolin .