I answer that, God's wisdom "orders all things sweetly" (Wis. 8:1), inasmuch as His providence appoints to each one that which is befitting it according to its nature. For as Dionysius says (Div. Nom. iv), "it belongs to providence not to destroy, but to maintain, nature." Now it is a condition attaching to human nature that one creature can be helped or impeded by another. Wherefore it was fitting that God should both allow man in the state of innocence to be tempted by evil angels, and should cause him to be helped by good angels. And by a special favor of grace, it was granted him that no creature outside himself could harm him against his own will, whereby he was able even to resist the temptation of the demon.
Reply Obj. 1: Above the human nature there is another that admits of the possibility of the evil of fault: but there is not above the angelic nature. Now only one that is already become evil through sin can tempt by leading another into evil. Hence it was fitting that by an evil angel man should be tempted to sin, even as according to the order of nature he is moved forward to perfection by means of a good angel. An angel could be perfected in good by something above him, namely by God, but he could not thus be led into sin, because according to James 1:13, "God is not a tempter of evils."
Reply Obj. 2: Just as God knew that man, through being tempted, would fall into sin, so too He knew that man was able, by his free will, to resist the tempter. Now the condition attaching to man's nature required that he should be left to his own will, according to Ecclus. 15:14, "God left" man "in the hand of his own counsel." Hence Augustine says (Gen. ad lit. xi, 4): "It seems to me that man would have had no prospect of any special praise, if he were able to lead a good life simply because there was none to persuade him to lead an evil life; since both by nature he had the power, and in his power he had the will, not to consent to the persuader."
Reply Obj. 3: An assault is penal if it be difficult to resist it: but, in the state of innocence, man was able, without any difficulty, to resist temptation. Consequently the tempter's assault was not a punishment to man. _______________________
SECOND ARTICLE [II-II, Q. 165, Art. 2]
Whether the Manner and Order of the First Temptation Was Fitting?
Objection 1: It would seem that the manner and order of the first temptation was not fitting. For just as in the order of nature the angel was above man, so was the man above the woman. Now sin came upon man through an angel: therefore in like manner it should have come upon the woman through the man; in other words the woman should have been tempted by the man, and not the other way about.
Obj. 2: Further, the temptation of our first parents was by suggestion. Now the devil is able to make suggestions to man without making use of an outward sensible creature. Since then our first parents were endowed with a spiritual mind, and adhered less to sensible than to intelligible things, it would have been more fitting for man to be tempted with a merely spiritual, instead of an outward, temptation.
Obj. 3: Further, one cannot fittingly suggest an evil except through some apparent good. But many other animals have a greater appearance of good than the serpent has. Therefore man was unfittingly tempted by the devil through a serpent.
Obj. 4: Further, the serpent is an irrational animal. Now wisdom, speech, and punishment are not befitting an irrational animal. Therefore the serpent is unfittingly described (Gen. 3:1) as "more subtle than any of the beasts of the earth," or as "the most prudent of all beasts" according to another version [*The Septuagint]: and likewise is unfittingly stated to have spoken to the woman, and to have been punished by God.