Complex sentence: Still kept at the woolen mill in Killin, are a set of river stones which were believed to have been given healing powers by St. Fillan and a particular sequence of movements of an appropriate stone around the afflicted area was believed to result in a cure.
Split into simpler sentences: Still kept at the woollen mill in Killin are a set of river stones which were believed to have been given healing powers by St. Fillan. A particular sequence of movements of an appropriate stone around the afflicted area was believed to result in a cure.