962. Therefore, the succenturiate kidneys take away the impurities of the spirits of the blood, and the kidneys the impurities of the serum of the blood, and this in a like manner as it were. They act by attraction, the organ doing the acting. The spirits of that province act in a similar manner. They are such that as soon as anything corresponding in the purer sphere is excited, then, since the corporeal things which the man or soul has with him cannot be separated, therefore by a cooperative force, which acts at a distance according to the sphere of their activity, they associate themselves, excite, attract, and so free the better and purer things from the more impure, even from those that are foul and putrid. Wherefore it is evil spirits who drive such things away. They do not on that account become worse, however, for they must perform such functions before they become better, or are reformed.