From
A Gnostic Prayer Book:
To exorcise is to call up or conjure spirits or to chain an isolated spirit.
In relation with conjurations, the book also says:
To conjure (Latin, cum-jurare; to swear together) is to invoke a superior force in order to reject its opposite or inferior force. To conjure is to make a common act of faith with the invoked force or forces. The greater the strength and enthusiasm of this faith, the more efficacious the conjuration will be.
To invoke the spirits of the elements is to work with nature under the direction of Christ for the benefit of all beings, in accordance with divine will, the great Law of destiny, and the universal charity and compassion.