I am reversing the order of the quotes, because it is better to read Calvin, who has the principle, and at this time then Aquinas, who has examples of this. The principle is that we cannot comprehend God. At all. The spirit of God was given to us so we can comprehend the mind of God, and the spirit has to be cultivated.
In short, we cannot understand our design because we were not the designer.
An example before we get into the theologians. I’m moderately intelligent, about two to three standard deviations above the norm. I enjoy reading people who are geniuses. There are areas where I am considered an expert. But I am very aware of the difficulties with the data. When I hear people quoting things that I wrote, or analyzed, as if it is a truth written in hardened concrete I cringe. I’m aware how much I can be a doofus, and in error. I am aware that the evidence from trials changes over time: new work informs old work, and old work informs new work.
And I do not fully understand the very thing that I am an expert in. But I’ve never claimed to be God. Our understanding is partial. Calvin speaks bleak truth when he says the minds of men have not capacity enough to know their calling
21. What the Apostle here denies to man, he, in another place, ascribes to God alone, when he prays, “that the God of our Lord Jesus Christ, the Father of glory, may give unto you the spirit of wisdom and revelation,” (Eph. 1:17). You now hear that all wisdom and revelation is the gift of God. What follows? “The eyes of your understanding being enlightened.” Surely, if they require a new enlightening, they must in themselves be blind. The next words are, “that ye may know what is the hope of his calling,” (Eph. 1:18). In other words, . Let no prating Pelagian here allege that God obviates this rudeness or stupidity, when, by the doctrine of his word, he directs us to a path which we could not have found without a guide. David had the law, comprehending in it all the wisdom that could be desired, and yet not contented with this, he prays, “Open thou mine eyes, that I may behold wondrous things out of thy law,” (Ps. 119:18). By this expression, he certainly intimates, that it is like sunrise to the earth when the word of God shines forth; but that men do not derive much benefit from it until he himself, who is for this reason called the Father of lights (James 1:17), either gives eyes or opens them; because, whatever is not illuminated by his Spirit is wholly darkness. The Apostles had been duly and amply instructed by the best of teachers. Still, as they wanted the Spirit of truth to complete their education in the very doctrine which they had previously heard, they were ordered to wait for him (John 14:26). If we confess that what we ask of God is lacking to us, and He by the very thing promised intimates our want, no man can hesitate to acknowledge that he is able to understand the mysteries of God, only in so far as illuminated by his grace. He who ascribes to himself more understanding than this, is the blinder for not acknowledging his blindness.
22. It remains to consider the third branch of the knowledge of spiritual things–viz. the method of properly regulating the conduct. This is correctly termed the knowledge of the works of righteousness, a branch in which the human mind seems to have somewhat more discernment than in the former two, since an Apostle declares, “When the Gentiles, which have not the law, do by nature the things contained in the law, these, having not the law, are a law unto themselves: which show the work of the law written in their hearts, their conscience also bearing witness, and their thoughts the meantime accusing or else excusing one another” (Rom. 2:14, 15). If the Gentiles have the righteousness of the law naturally engraven on their minds, we certainly cannot say that they are altogether blind as to the rule of life. Nothing, indeed is more common, than for man to be sufficiently instructed in a right course of conduct by natural law, of which the Apostle here speaks. Let us consider, however for what end this knowledge of the law was given to men. For from this it will forthwith appear how far it can conduct them in the way of reason and truth. This is even plain from the words of Paul, if we attend to their arrangement. He had said a little before, that those who had sinned in the law will be judged by the law; and those who have sinned without the law will perish without the law. As it might seem unaccountable that the Gentiles should perish without any previous judgment, he immediately subjoins, that conscience served them instead of the law, and was therefore sufficient for their righteous condemnation. The end of the natural law, therefore, is to render man inexcusable, and may be not improperly defined–the judgment of conscience distinguishing sufficiently between just and unjust, and by convicting men on their own testimony depriving them of all pretext for ignorance. So indulgent is man towards himself, that, while doing evil, he always endeavours as much as he can to suppress the idea of sin. It was this, apparently, which induced Plato (in his Protagoras) to suppose that sins were committed only through ignorance. There might be some ground for this, if hypocrisy were so successful in hiding vice as to keep the conscience clear in the sight of God. But since the sinner, when trying to evade the judgment of good and evil implanted in him, is ever and anon dragged forward, and not permitted to wink so effectually as not to be compelled at times, whether he will or not, to open his eyes, it is false to say that he sins only through ignorance.
Now to Aquinas. He is continuing to work through the errors in the Incarnation, systematically. Very, very systematically.
1 From the things set down, therefore, it appears that Christ was not without divine nature, as Ebion, Cerinthus, and Photinus said; nor without a true human body, as in the error of Mani and Valentine; nor without a human soul, as Arius and Apollinaris held. Since, then, these three substances met in Christ—namely, divinity, the human soul, and the true human body—what one should think about their union following the Scriptural teachings remains for inquiry.
2 Now, then, Theodore of Mopsueste and Nestorius, his follower, offered one sort of opinion on the aforesaid union. They said that the human soul and the true human body came together in Christ by a natural union to constitute one man of the same species and nature with other men, and that in this man God dwelt as in His temple, namely, by grace, just as in other holy men.
Hence, it says in John (2:19, 21), that He said to the Jews: “Destroy this temple and in three days I will raise it up”; and later the Evangelist by way of exposition adds: “But he spoke of the temple of His body”; and the Apostle says: “In Him it has well pleased the Father, that all fullness should dwell” (Col. 1:19). And out of these arose further a certain affective union between that man and God, when that man cleaved to God with his own good will, and God lifted up that man with His will, in the words of John (8:29): “He that sent me is with me, and He has not left me alone: for I do always the things that please Him.” Let one thus understand that the union of that man to God is such as was the union of which the Apostle said: “He who is joined to God is one spirit” (1 Cor. 6:17).
And just as, from the latter union, names which properly befit God are transferred to men so that they are called “gods,” and “sons of God,” and “lords,” and “holy ones,” and “christs”, as is clear from a diversity of places in Scripture; so also the divine names befit that man so that, by reason of God’s indwelling and the affective union, he is called God, and the Son of God, and Holy, and Christ. Nonetheless, because there was in that man a greater fullness of grace than in other holy men, he was before all the rest the temple of God, he was united to God, more closely in affection, and it was by a singular kind of privilege that he shared the divine names. And because of this outstanding grace he was established in a share of the divine dignity and honor; namely, that he be co-adored with God. So, then, consequently on the things just said there must be one Person of the Word of God, and another person of that man who is co-adored with the Word of God. And if one Person of each of the two be mentioned, this will be by reason of the affective union aforesaid; so that man and the Word of God may be called one Person, as is said of man and woman that “now they are not two, but one flesh” (Mat. 19:6).
Now, such a union does not bring it about that what is said of the first can be said of the second (for not everything which becomes the man is true of the woman, or conversely); therefore in the union of the Word and that man they think this must be observed: The things proper to that man and pertinent to the human nature cannot be said becomingly of God’s Word, or of God. just so it becomes that man that he was born of a virgin, that he suffered, died, was buried, and this kind of thing; and all of these, they assert, ought not be said of God, or of the Word of God.
But, since there are certain names which, although they are chiefly befitting to God, are nonetheless communicated to men in a fashion—“christ,” for instance, “lord,” “holy,” and even “son of God”—nothing according to them keeps one from the use of such names in predication of the things just mentioned. For, according to them, we say fittingly that Christ, or the “Lord of glory,” or the “Saint of saints,” or “God’s son” was born of a virgin, suffered, died and was buried. Hence, too, the Blessed Virgin must not be named the mother of God, or of the Word of God, but the mother of Christ, they say.
3 But let one earnestly consider the matter and he will see that the position described excludes the truth of the Incarnation. For, in that position, the Word of God was united to that man only through an indwelling by grace, on which a union of wills follows. But the indwelling of God’s Word in a man is not for God’s Word to be made flesh. For the Word of God and God Himself have been dwelling in all the holy men since the world was founded; as the Apostle says: “You are the temple of the living God; as God says: I will dwell in them” (2 Cor. 6: 16).
And this indwelling, for all that, cannot be called incarnation; otherwise, God would have repeatedly been made flesh since the beginning of the world. Nor does it suffice for the notion of incarnation if the Word of God or God dwelt in that man with a fuller grace, for “greater and less do not diversify the species of union.” Since the Christian religion is based on faith in the Incarnation, it is now quite evident that the position described removes the basis of the Christian religion.
4 In addition is the very manner of speech of Scripture, which makes the falsity of the position described plain. For the indwelling of the Word of God in holy men is usually designated by Scripture in these ways: “The Lord spoke to Moses”; “the word of the Lord came to Jeremiah” (or to some other Prophet); “The word of the Lord came to the hand of Haggai the Prophet.” But one never reads the Word of the Lord was made Moses, or Jeremiah, or one of the others. Yet thus uniquely was the union of God’s Word to the flesh of Christ marked by the Evangelist: “The Word was made flesh,” as was explained before. Clearly, then, it was not by indwelling alone that God’s Word was in the man, Christ, if we follow Scripture.
When reading systematic theology, I do not look for the conflict. Each theologian is striving to understanding that which can only be understood by the mind of God. This is something that all agree on. I look for the unity: in correction, in teaching. Otherwise we will be divided, and disavow our brothers in Christ.
The question is how to discern the spirit of God. Here we have a few guidelines.
The first is the spirit of God is always in agreement with the revealed word of God. If you consider tradition as a gloss on the words of the apostles, prophets, law and the gospel, then you are doing well. Neither the spirit of God nor the righteous traditions we have twist or deny scripture.
The second is that the spirit of God is never of fear, but tells us not to fear.
The third is that the spirit guides us to truth, and not obvious lies. The spirit of God brings love, joy, peace, patience, kindness, goodness and increases our Godly behaviour. It leads us into the fulness of whom we are. The spirit of the age is the opposite.
And the final is that the spirit of sound doctrine does not change — over the generations (this is a good teaching from the Orthodox) and is agreed from in all places and all branches that have not degenerated. (The degenerated branches of the church die rapidly, with all too often the same errors. Consider how the Shakers have similar theology to the Cathars, and the modern feminist theology).
We cannot understand the mind of God. One reason for the incarnation is that God is merciful: we could see Christ, when the presence of God is beyond us since the fall.