1 He has therefore, in His work of recapitulation, summed up all things, both waging war against our enemy, and crushing him who had at the beginning led us away captives in Adam, and trampled upon his head, as you can perceive in Genesis that God said to the serpent, “And I will put enmity between you and the woman, and between your seed and her seed; He shall be on the watch for (observabit) your head, and you on the watch for His heel.” For from that time, He who should be born of a woman, [namely] from the Virgin, after the likeness of Adam, was preached as keeping watch for the head of the serpent. This is the seed of which the apostle says in the Epistle to the Galatians, “that the law of works was established until the seed should come to whom the promise was made.” This fact is exhibited in a still clearer light in the same Epistle, where he thus speaks: “But when the fullness of time had come, God sent forth His Son, made of a woman.” For indeed the enemy would not have been fairly vanquished, unless it had been a man [born] of a woman who conquered him. For it was by means of a woman that he got the advantage over man at first, setting himself up as man's opponent. And therefore does the Lord profess Himself to be the Son of man, comprising in Himself that original man out of whom the woman was fashioned (ex quo ea quæ secundum mulierem est plasmatio facta est), in order that, as our species went down to death through a vanquished man, so we may ascend to life again through a victorious one; and as through a man death received the palm [of victory] against us, so again by a man we may receive the palm against death.
2. Now the Lord would not have recapitulated in Himself that ancient and primary enmity against the serpent, fulfilling the promise of the Creator (Demiurgi), and performing His command, if He had come from another Father. But as He is one and the same, who formed us at the beginning, and sent His Son at the end, the Lord did perform His command, being made of a woman, by both destroying our adversary, and perfecting man after the image and likeness of God. And for this reason He did not draw the means of confounding him from any other source than from the words of the law, and made use of the Father's commandment as a help towards the destruction and confusion of the apostate angel. Fasting forty days, like Moses and Elias, He afterwards hungered, first, in order that we may perceive that He was a real and substantial man— for it belongs to a man to suffer hunger when fasting; and secondly, that His opponent might have an opportunity of attacking Him. For as at the beginning it was by means of food that [the enemy] persuaded man, although not suffering hunger, to transgress God's commandments, so in the end he did not succeed in persuading Him that was an hungered to take that food which proceeded from God. For, when tempting Him, he said, “If you be the Son of God, command that these stones be made bread.” But the Lord repulsed him by the commandment of the law, saying, “It is written, Man does not live by bread alone.” As to those words [of His enemy,] “If you be the Son of God,” [the Lord] made no remark; but by thus acknowledging His human nature He baffled His adversary, and exhausted the force of his first attack by means of His Father's word. The corruption of man, therefore, which occurred in paradise by both [of our first parents] eating, was done away with by [the Lord's] want of food in this world. But he, being thus vanquished by the law, endeavoured again to make an assault by himself quoting a commandment of the law. For, bringing Him to the highest pinnacle of the temple, he said to Him, “If you are the Son of God, cast yourself down. For it is written, That God shall give His angels charge concerning you, and in their hands they shall bear you up, lest perchance you dash your foot against a stone;” thus concealing a falsehood under the guise of Scripture, as is done by all the heretics. For that was indeed written, [namely], “That He has given His angels charge concerning Him;” but “cast yourself down from hence” no Scripture said in reference to Him: this kind of persuasion the devil produced from himself. The Lord therefore confuted him out of the law, when He said, “It is written again, You shall not tempt the Lord your God;” pointing out by the word contained in the law that which is the duty of man, that he should not tempt God; and in regard to Himself, since He appeared in human form, [declaring] that He would not tempt the Lord his God. The pride of reason, therefore, which was in the serpent, was put to nought by the humility found in the man [Christ], and now twice was the devil conquered from Scripture, when he was detected as advising things contrary to God's commandment, and was shown to be the enemy of God by [the expression of] his thoughts. He then, having been thus signally defeated, and then, as it were, concentrating his forces, drawing up in order all his available power for falsehood, in the third place “showed Him all the kingdoms of the world, and the glory of them,” saying, as Luke relates, “All these will I give you—for they are delivered to me; and to whom I will, I give them—if you will fall down and worship me.” The Lord then, exposing him in his true character, says, “Depart, Satan; for it is written, You shall worship the Lord your God, and Him only shall you serve.” He both revealed him by this name, and showed [at the same time] who He Himself was. For the Hebrew word “Satan” signifies an apostate. And thus, vanquishing him for the third time, He spurned him from Him finally as being conquered out of the law; and there was done away with that infringement of God's commandment which had occurred in Adam, by means of the precept of the law, which the Son of man observed, who did not transgress the commandment of God.
3. Who, then, is this Lord God to whom Christ bears witness, whom no man shall tempt, whom all should worship, and serve Him alone? It is, beyond all manner of doubt, that God who also gave the law. For these things had been predicted in the law, and by the words (sententiam) of the law the Lord showed that the law does indeed declare the Word of God from the Father; and the apostate angel of God is destroyed by its voice, being exposed in his true colours, and vanquished by the Son of man keeping the commandment of God. For as in the beginning he enticed man to transgress his Maker's law, and thereby got him into his power; yet his power consists in transgression and apostasy, and with these he bound man [to himself]; so again, on the other hand, it was necessary that through man himself he should, when conquered, be bound with the same chains with which he had bound man, in order that man, being set free, might return to his Lord, leaving to him (Satan) those bonds by which he himself had been fettered, that is, sin. For when Satan is bound, man is set free; since “none can enter a strong man's house and spoil his goods, unless he first bind the strong man himself.” The Lord therefore exposes him as speaking contrary to the word of that God who made all things, and subdues him by means of the commandment. Now the law is the commandment of God. The Man proves him to be a fugitive from and a transgressor of the law, an apostate also from God. After [the Man had done this], the Word bound him securely as a fugitive from Himself, and made spoil of his goods,— namely, those men whom he held in bondage, and whom he unjustly used for his own purposes. And justly indeed is he led captive, who had led men unjustly into bondage; while man, who had been led captive in times past, was rescued from the grasp of his possessor, according to the tender mercy of God the Father, who had compassion on His own handiwork, and gave to it salvation, restoring it by means of the Word— that is, by Christ— in order that men might learn by actual proof that he receives incorruptibility not of himself, but by the free gift of God.
Source: Adversus haereses (New Advent)