’Potency’means1asourceofmovementorchange，whichisin
anotherthingthanthethingmovedorinthesamethingquaother；
e。g。theartofbuildingisapotencywhichisnotinthethingbuilt，
whiletheartofhealing，whichisapotency，maybeintheman
healed，butnotinhimquahealed。’Potency’thenmeansthesource，in