It’s a miracle!
1 Things that are at times divinely accomplished, apart from the generally established order in things, are customarily called miracles; for we admire with some astonishment a certain event when we observe the effect but do not know its cause.
And since one and the same cause is at times known to some people and unknown to others, the result is that of several who see an effect at the same time, some are moved to admiring astonishment, while others are not.
For instance, the astronomer is not astonished when he sees an eclipse of the sun, for he knows its cause, but the person who is ignorant of this science must be amazed, for he ignores the cause. And so, a certain event is wondrous to one person, but not so to another.
So, a thing that has a completely hidden cause is wondrous in an unqualified way, and this the name, miracle, suggests; namely, what is of itself filled with admirable wonder, not simply in relation to one person or another.
Now, absolutely speaking, the cause hidden from every man is God. In fact, we proved above that no man in the present state of life can grasp His essence intellectually. Therefore, those things must properly be called miraculous which are done by divine power apart from the order generally followed in things.
Notes There has to be more to it than this for the causes of QM events are not known, and are believed to be hidden from us in a wondrous, unqualified way. These causes are, to Aquinas, God. Which might very well be true. At least, it is true at the foundational level, i.e. the first cause.
2 Now, there are various degrees and orders of these miracles. Indeed, the highest rank among miracles is held by those events in which something is done by God which nature never could do. For example, that two bodies should be coincident; that the sun reverse its course, or stand still; that the sea open up and offer a way through which people may pass.
And even among these an order may be observed. For the greater the things that God does are, and the more they are removed from the capacity of nature, the greater the miracle is. Thus, it is more miraculous for the sun to reverse its course than for the sea to be divided.
Notes This hints that greater powers are needed for greater effects.
3 Then, the second degree among miracles is held by those events in which God does something which nature can do, but not in this order. It is a work of nature for an animal to live, to see, and to walk; but for it to live after death, to see after becoming blind, to walk after paralysis of the limbs, this nature cannot do—but God at times does such works miraculously. Even among this degree of miracles a gradation is evident, according as what is done is more removed from the capacity of nature.
Notes Removed from the capacity of nature means that a thing acts in a way other than accord with its essence, such as man flying.
4 Now, the third degree of miracles occurs when God does what is usually done by the working of nature, but without the operation of the principles of nature. For example, a person may be cured by divine power from a fever which could be cured naturally, and it may rain independently of the working of the principles of nature.
Notes These are the smallest miracles, in a sense, but only because they are more difficult for people to believe. They mean of immense personal importance.