"I answer that, As stated in the preceding article, there are two ways of adjuring: one by way of prayer or inducement through reverence of some holy thing: the other by way of compulsion. In the first way it is not lawful to adjure the demons because such a way seems to savor of benevolence or friendship, which it is unlawful to bear towards the demons. As to the second kind of adjuration, which is by compulsion, we may lawfully use it for some purposes, and not for others. For during the course of this life the demons are our adversaries: and their actions are not subject to our disposal but to that of God and the holy angels, because, as Augustine says (De Trin. iii, 4), "the rebel spirit is ruled by the just spirit." Accordingly we may repulse the demons, as being our enemies, by adjuring them through the power of God's name, lest they do us harm of soul or body, in accord with the Divine power given by Christ, as recorded by Lk. 10:19: "Behold, I have given you power to tread upon serpents and scorpions, and upon all the power of the enemy: and nothing shall hurt you."
Aquin.: SMT SS Q[90] A[2] Body Para. 2/2