On the Natural, Artificial, Preternatural and Supernatural, and on miracles

The Natural, Artificial, Preternatural and Supernatural refer to an action or act each belonging to a different sphere. they are differentiated from the point of view of the subject, not so much the object.
The Subject of the natural is nature, of the artificial is man, of the preternatural is a spirit and of the supernatural is God.
So the Object of this action may be exactly the same, the moving of a stone. but the subject who performs this action may be different. If there were a earthquake and the stone was to fall, the action would belong to the natural sphere. A stone thrown by a man would belong to the artificial sphere, thrown by a demon, to the preternatural sphere and finally turn into children of Abraham by God, to the supernatural sphere.
Now miracles can be defined as an action by which God, transcending the ordinary course of nature, gives testimony of himself. This would mean that miracles belong to the supernatural sphere.

One of the important words in this definition is "testimony", because it is the final cause of the miracle, to give testimony to God. One of the ways we know that a message comes from God, or that a Saint is a man of God , is done by the testimony of miracles. Without miracles no one could be canonised, the Church would be incapable of deciding for or against apparitions or the such like.

Another important word is "transcends", because a miracle must be incapable of having a so called rational explanation. this is the formal cause. It is necessary for a miracle to "transcend the ordinary course of nature", if not it is not a miracle. The birth of a child does not transcend the ordinary course of nature , it is therefore not a miracle.

Another important word is "God" because he is the efficient cause, if the miracle does not have God as author, then it is not a miracle but a prodigy or an artifice. A prodigy being analogically a miracle in the preternatural sphere.

The material cause is the action itself.