William Briggs notes that Aquinas has been going down a windy path, listing efter error on the trinity. It hurt my hed. This is bad enough. Calvin discusses here how we have a general sense of justice and injustice but we blind ourselves to our own errors.
And his argument, though more plain, is painfully accurate.
24. Moreover, when you hear of a universal judgment in man distinguishing between good and evil, you must not suppose that this judgment is, in every respect, sound and entire. For if the hearts of men are imbued with a sense of justice and injustice, in order that they may have no pretext to allege ignorance, it is by no means necessary for this purpose that they should discern the truth in particular cases. It is even more than sufficient if they understand so far as to be unable to practice evasion without being convicted by their own conscience, and beginning even now to tremble at the judgment-seat of God. Indeed, if we would test our reason by the Divine Law, which is a perfect standard of righteousness, we should find how blind it is in many respects. It certainly attains not to the principal heads in the First Table, such as, trust in God, the ascription to him of all praise in virtue and righteousness, the invocation of his name, and the true observance of his day of rest. Did ever any soul, under the guidance of natural sense, imagine that these and the like constitute the legitimate worship of God? When profane men would worship God, how often soever they may be drawn off from their vain trifling, they constantly relapse into it. They admit, indeed, that sacrifices are not pleasing, to God, unless accompanied with sincerity of mind; and by this they testify that they have some conception of spiritual worship, though they immediately pervert it by false devices: for it is impossible to persuade them that every thing which the law enjoins on the subject is true. Shall I then extol the discernment of a mind which can neither acquire wisdom by itself, nor listen to advice? As to the precepts of the Second Table, there is considerably more knowledge of them, inasmuch as they are more closely connected with the preservation of civil society. Even here, however, there is something defective. Every man of understanding deems it most absurd to submit to unjust and tyrannical domination, provided it can by any means be thrown off, and there is but one opinion among men, that it is the part of an abject and servile mind to bear it patiently, the part of an honourable and high-spirited mind to rise up against it. Indeed, the revenge of injuries is not regarded by philosophers as a vice. But the Lord condemning this too lofty spirit, prescribes to his people that patience which mankind deem infamous. In regard to the general observance of the law, concupiscence altogether escapes our animadversion. For the natural man cannot bear to recognise diseases in his lusts. The light of nature is stifled sooner than take the first step into this profound abyss. For, when philosophers class immoderate movements of the mind among vices, they mean those which break forth and manifest themselves in grosser forms. Depraved desires, in which the mind can quietly indulge, they regard as nothing (see infra, chap. 8 sect. 49).
25. As we have above animadverted on Plato’s error, in ascribing all sins to ignorance, so we must repudiate the opinion of those who hold that all sins proceed from preconceived gravity and malice. We know too well from experience how often we fall, even when our intention is good. Our reason is exposed to so many forms of delusion, is liable to so many errors, stumbles on so many obstacles, is entangled by so many snares, that it is ever wandering from the right direction. Of how little value it is in the sight of God, in regard to all the parts of life, Paul shows, when he says, that we are not “sufficient of ourselves to think any thing as of ourselves,” (2 Cor. 3:5). He is not speaking of the will or affection; he denies us the power of thinking aright how any thing cam be duly performed. Is it, indeed, true, that all thought, intelligence, discernment, and industry, are so defective, that, in the sight of the Lord, we cannot think or aim at any thing that is right? To us, who can scarcely bear to part with acuteness of intellect (in our estimation a most precious endowment), it seems hard to admit this, whereas it is regarded as most just by the Holy Spirit, who “knoweth the thoughts of man, that they are vanity,” (Ps. 94:11), and distinctly declares, that “every imagination of the thoughts of his heart was only evil continually,” (Gen. 6:5; 8:21). If every thing which our mind conceives, meditates plans, and resolves, is always evil, how can it ever think of doing what is pleasing to God, to whom righteousness and holiness alone are acceptable? It is thus plain, that our mind, in what direction soever it turns, is miserably exposed to vanity. David was conscious of its weakness when he prayed, “Give me understanding, and I shall keep thy law,” (Ps. 119:34). By desiring to obtain a new understanding, he intimates that his own was by no means sufficient. This he does not once only, but in one psalm repeats the same prayer almost ten times, the repetition intimating how strong the necessity which urged him to pray. What he thus asked for himself alone, Paul prays for the churches in general. “For this cause,” says he, “we also, since the day we heard it, do not cease to pray for you, and to desire that ye might be filled with the knowledge of his will, in all wisdom and spiritual understanding; that you might walk worthy of the Lord,” &c. (Col. 1:9, 10). Whenever he represents this as a blessing from God, we should remember that he at the same time testifies that it is not in the power of man. Accordingly, Augustine, in speaking of this inability of human reason to understand the things of God, says, that he deems the grace of illumination not less necessary to the mind than the light of the sun to the eye (August. de Peccat. Merit. et Remiss. lib. 2 cap. 5). And, not content with this, he modifies his expression, adding, that we open our eyes to behold the light, whereas the mental eye remains shut, until it is opened by the Lord. Nor does Scripture say that our minds are illuminated in a single day, so as afterwards to see of themselves. The passage, which I lately quoted from the Apostle Paul, refers to continual progress and increase. David, too, expresses this distinctly in these words: “With my whole heart have I sought thee: O let me not wander from thy commandments,” (Ps. 119:10). Though he had been regenerated, and so had made no ordinary progress in true piety, he confesses that he stood in need of direction every moment, in order that he might not decline from the knowledge with which he had been endued. Hence, he elsewhere prays for a renewal of a right spirit, which he had lost by his sin, (Ps. 51:12). For that which God gave at first, while temporarily withdrawn, it is equally his province to restore.
Note well that the ancients considered ignorance the well of sin. They were wrong: it is in our nature. But the ancients would damn the post-moderns as sophists, seeing nothing but power.
The wise, instead, sin willingly, inadvertently, but it is not knowledge that picks them up when they fall. Instead it is the spirit of God, who calls all to Christ.