An objection whether unclean spirits can be present in or united with the souls of those whom they have filled.
Germanus: To this idea we think that what we see happen in the case of those possessed is sufficiently opposed, when they say and do what they know not under the influence of the spirits. How then are we to refuse to believe that their souls are not united to those spirits, when we see them made their instruments, and (forsaking their natural condition) yielding to their movements and moods, in such a way that they give expression no longer to their own words and actions and wishes, but to those of the demons?
Source: Conferences (New Advent)