Saint Thomas Aquitaine also refers to this in his writings about the existence of God. He is disproving the infidels (non-Christians) that God doesn't exist. He uses "efficient cause" as one his reasons for God's existence. "If there be no first cause among efficient causes, then there will be no ultimate, nor intermediate cause...Therefore it is necessary to admit a first efficient cause, to which everyone gives the name of God." (Exerpt from Summa Theologica Third Article: Whether God exists?) The Material Cause, that out of which the statue is made, is the marble or bronze. ... The Formal Cause, that according to which the statue is made, is the idea existing in the first place as exemplar in the mind of the sculptor, and in the second place as intrinsic, determining cause, embodied in the matter. ... Purpose is deliberately thought-through goal-directedness. ...
Cause, as the correlative of effect, is understood as being that which in any way gives existence to, or contributes towards the existence of, any thing; which produces a result; to which the origin of any thing is to be ascribed.
The moving, or efficient, cause, which, as will be seen later, is that which has come to be chiefly regarded as the true cause, and that round which most controversy has arisen, is, in this fourfold division of causes, that one by the operation or agency of which the effect is brought into being; i.e.
His criticism was aimed at the possibility of a knowledge of causal efficiency; and without an adequate theory of cognition, as well as a proper grasp of the relationships between efficientcause and effect in the process of becoming, the idea of efficiency, or power, is indeed inexplicable.