For as mothers are pregnant with young, so the world itself is pregnant with the causes of things that are born; which are not created in it, except from that highest essence, where nothing either springs up or dies, either begins to be or ceases. But the applying from without of adventitious causes, which, although they are not natural, yet are to be applied according to nature, in order that those things which are contained and hidden in the secret bosom of nature may break forth and be outwardly created in some way by the unfolding of the proper measures and numbers and weights which they have received in secret from Him "who has ordered all things in measure and number and weight:"  this is not only in the power of bad angels, but also of bad men, as I have shown above by the example of agriculture.
17. But lest the somewhat different condition of animals should trouble any one, in that they have the breath of life with the sense of desiring those things that are according to nature, and of avoiding those things that are contrary to it; we must consider also, how many men there are who know from what herbs or flesh, or from what juices or liquids you please, of whatever sort, whether so placed or so buried, or so bruised or so mixed, this or that animal is commonly born; yet who can be so foolish as to dare to call himself the creator of these animals? Is it, therefore, to be wondered at, if just as any, the most worthless of men, can know whence such or such worms and flies are produced; so the evil angels in proportion to the subtlety of their perceptions discern in the more hidden seeds of the elements whence frogs and serpents are produced, and so through certain and known opportune combinations applying these seeds by secret movements, cause them to be created, but do not create them? Only men do not marvel at those things that are usually done by men. But if any one chance to wonder at the quickness of those growths, in that those living beings were so quickly made, let him consider how even this may be brought about by men in proportion to the measure of human capability. For whence is it that the same bodies generate worms more quickly in summer than in winter, or in hotter than in colder places? Only these things are applied by men with so much the more difficulty, in proportion as their earthly and sluggish members are wanting in subtlety of perception, and in rapidity of bodily motion. And hence it arises that in the case of any kind of angels, in proportion as it is easier for them to draw out the proximate causes from the elements, so much the more marvellous is their rapidity in works of this kind.
18. But He only is the creator who is the chief former of these things. Neither can any one be this, unless He with whom primarily rests the measure, number, and weight of all things existing; and He is God the one Creator, by whose unspeakable power it comes to pass, also, that what these angels were able to do if they were permitted, they are therefore not able to do because they are not permitted. For there is no other reason why they who made frogs and serpents were not able to make the most minute flies, unless because the greater power of God was present prohibiting them, through the Holy Spirit; which even the magicians themselves confessed, saying, "This is the finger of God."  But what they are able to do by nature, yet cannot do, because they are prohibited; and what the very condition of their nature itself does not suffer them to do; it is difficult, nay, impossible, for man to search out, unless through that gift of God which the apostle mentions when he says, "To another the discerning of spirits."  For we know that a man can walk, yet that he cannot do so if he is not permitted; but that he cannot fly, even if he be permitted. So those angels, also, are able to do certain things if they are permitted by more powerful angels, according to the supreme commandment of God; but cannot do certain other things, not even if they are permitted by them; because He does not permit from whom they have received such and such a measure of natural powers: who, even by His angels, does not usually permit what He has given them power to be able to do.
19. Excepting, therefore, those corporeal things which are done in the order of nature in a perfectly usual series of times, as e.g., the rising and setting of the stars, the generations and deaths of animals, the innumerable diversities of seeds and buds, the vapors and the clouds, the snow and the rain, the lightnings and the thunder, the thunderbolts and the hail, the winds and the fire, cold and heat, and all like things; excepting also those which in the same order of nature occur rarely, such as eclipses, unusual appearances of stars, and monsters, and earthquakes, and such like; -- all these, I say, are to be excepted, of which indeed the first and chief cause is only the will of God; whence also in the Psalm, when some things of this kind had been mentioned, "Fire and hail, snow and vapor, stormy wind," lest any one should think those to be brought about either by chance or only from corporeal causes, or even from such as are spiritual, but exist apart from the will of God, it is added immediately, "fulfilling His word." 
 [This is the same as the theological distinction between substances and their modifications. "The former," says Howe, "are the proper object of creation strictly taken; the modifications of things are not properly created, in the strictest sense of creation, but are educed and brought forth out of those substantial things that were themselves created, or made out of nothing."--Germs are originated ex nihilo, and fall under creation proper; their evolution and development takes place according to the nature and inherent force of the germ, and falls under providence, in distinction from creation. See the writer's Theological Essays, 133-137.--W.G.T.S.]  Wisd. xi. 20  Exodus 7:12, and viii. 7, 18, 19  1 Corinthians 12:10  Psalm 148:8
 Wisd. xi. 20
 Exodus 7:12, and viii. 7, 18, 19
 1 Corinthians 12:10
 Psalm 148:8