“ But as we do not know all the power of created nature, it follows that when anything is done outside the order of created nature by a power unknown to us, it is called a miracle as regards ourselves. ”
 Thomas Aquinas, Summa Theologica (1274). copy citation

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“1: Some angels are said to work miracles; either because God works miracles at their request, in the same way as holy men are said to work miracles; or because they exercise a kind of ministry in the miracles which take place; as in collecting the dust in the general resurrection, or by doing something of that kind.
Reply Obj. 2: Properly speaking, as said above, miracles are those things which are done outside the order of the whole created nature. But as we do not know all the power of created nature, it follows that when anything is done outside the order of created nature by a power unknown to us, it is called a miracle as regards ourselves. So when the demons do anything of their own natural power, these things are called "miracles" not in an absolute sense, but in reference to ourselves. In this way the magicians work miracles through the demons; and these are said to be done by "private contracts," forasmuch as every power of the creature, in the universe, may be compared to the power of a private person in a city.” source