In this fourth post in our series on Aquinas and the Council of Trent, I examine what St. Thomas Aquinas says about another effect of sin, namely, stain in the soul. How does sin cause a stain in the soul? What is this stain? Is it caused by all sins or only mortal sins? Does it remain in the soul after the sinful act is concluded?

The Temptation of St. Thomas Aquinas¹
Bernardo Daddi (1338)

St. Thomas Aquinas on Stain in the Soul as an Effect of Sin

“Therefore beloved, since you look for these things, be diligent to be found by Him in peace, spotless and blameless.” (2 Peter 3:14)

In order to understand the Catholic Church’s teaching on salvation, one must first understand her teaching on the fallen human condition. That is why the Council of Trent first put forward the Church’s position on original sin before turning to the subject of justification. And the theology of St. Thomas Aquinas, as I argued in Part 1, played a very significant role in the deliberation of the Tridentine Fathers. So in this series, we are looking at those areas of the theology of St. Thomas Aquinas that help us understand the theological rationale behind Session 5 and Session 6 of the Council of Trent, on original sin and justification, respectively. In my previous post in this series, I began to explain what Aquinas says about the effects of sin. Aquinas says that sin has three effects: corruption, stain, and debt.² In that post I explained what Aquinas says about corruption of our nature as an effect of sin. Here, in this post, I examine and explain what Aquinas says about stain of the soul as an effect of sin.

The Soul’s Twofold Comeliness

Concerning the stain of the soul, Aquinas writes:

A stain [macula] is properly ascribed to corporeal things, when a comely body loses its comeliness through contact with another body, e.g. a garment, gold or silver, or the like. Accordingly a stain is ascribed to spiritual things in like manner. Now man’s soul has a twofold comeliness; one from the refulgence of the natural light of reason, whereby he is directed in his actions; the other, from the refulgence of the Divine light, viz. of wisdom and grace, whereby man is also perfected for the purpose of doing good and fitting actions.³

Aquinas says that the human soul has a twofold comeliness [nitorem]. This term means brightness, radiance or beauty. One way in which the human soul has comeliness is by the refulgence [refulgentia] or reflection in it of the natural light of reason. The more perfectly the lower powers of the soul are ordered to the soul’s highest power, i.e. reason, such that they submit to it, the more perfectly the natural light of reason is reflected throughout the soul. The other way in which the human soul has comeliness is by the refulgence of the Divine light, i.e. wisdom and grace [sapientiae et gratiae], by which man is also perfected for the purpose of doing good and fitting actions.⁴

The wisdom Aquinas refers to here is not natural wisdom, i.e. an intellectual virtue that could be acquired by the unaided power of human reason. Aquinas is here referring to the supernatural gift of wisdom, which is a gift of the Holy Spirit, and which follows upon the supernatural gift of charity.⁵ It is worth considering this gift of wisdom more carefully. Concerning this supernatural wisdom Aquinas writes:

As stated above (Article 1), wisdom denotes a certain rectitude of judgment according to the Eternal Law. Now rectitude of judgment is twofold: first, on account of perfect use of reason, secondly, on account of a certain connaturality with the matter about which one has to judge [connaturalitatem quandam ad ea de quibus iam est iudicandum]. Thus, about matters of chastity, a man after inquiring with his reason forms a right judgment, if he has learnt the science of morals, while he who has the habit of chastity judges of such matters by a kind of connaturality.⁶

Aquinas notes that there are two ways in which right judgment can take place. One is by the perfect use of reason [by ‘perfect’ here he simply means proper], and the other is by a connaturality to that of which one is to judge. ‘Connaturality’ means a kind of sharing of the same nature, in some respect. In the encounter of that which is connatural to oneself, one finds that one already knows the other insofar as one knows one’s own nature.⁷ The encounter of that which is connatural to oneself allows one to judge concerning the other by ‘seeing’ the other within (i.e. by the light of) one’s own nature, either one’s primary nature (i.e. human nature) or one’s second nature (i.e. acquired nature in the sense of acquired habits), or even one’s participation in the divine nature.

As an example of the difference between judging by reasoning and judging by connaturality, Aquinas describes two ways in which someone may judge rightly regarding what should be done in a matter of chastity. One man by deduction reasons from first principles to determine correctly what is the chaste action to be done. Another man, let us say, has no formal training in the science of ethics but has the virtue of chastity. This man reaches the same correct conclusion about what is the chaste action to be done, yet he reaches this conclusion without reasoning through a syllogism. He simply sees this action as what chastity requires in these circumstances. The virtue of chastity in his soul as a kind of second nature works ‘upward’ through his cogitative faculty, such that even without deliberation or deduction he sees clearly the chaste course of action by a kind of connaturality with chastity and the circumstances before him, even though he may not be able to explain why that is the chaste course of action.⁸ His virtuous disposition toward chastity illumines to his intellect the chaste action to be done.

In a similar way, argues Aquinas, the supernatural gift of wisdom allows a man to judge rightly about Divine things, by a kind of connatural seeing without deliberation. He writes:

Accordingly it belongs to the wisdom that is an intellectual virtue to pronounce right judgment about Divine things after reason has made its inquiry, but it belongs to wisdom as a gift of the Holy Ghost to judge aright about them on account of connaturality with them …. Now this sympathy or connaturality for Divine things is the result of charity, which unites us to God, according to 1 Corinthians 6:17: “He who is joined to the Lord, is one spirit.” Consequently wisdom which is a gift, has its cause in the will, which cause is charity, but it has its essence in the intellect, whose act is to judge aright, as stated above (I-II, 14, 1).⁶

By the natural wisdom that is a virtue of the intellect a man may reason correctly to conclusions about Divine things. But there is also a supernatural wisdom which is a gift of the Holy Spirit, and by this gift one judges rightly concerning Divine things through a kind of connaturality with them. This connaturality with divine things, according to Aquinas, is the result of the theological virtue of charity, which is a supernatural gift along with faith and hope. Since by the natural love of friendship the beloved is one in spirit with the lover, so a fortiori by the supernatural gift of charity the beloved is one in spirit with the divine Lover. Aquinas quotes 1 Corinthians 6:17 in support of this conclusion.⁹ The one who has the supernatural gift of charity loves God above all other things. And with that love of God comes a mutual indwelling: “He that abides in charity abides in God, and God in him.” (1 John 4:16)

Concerning this mutual indwelling that results from charity, Aquinas says, “Therefore, for the same reason, every love makes the beloved to be in the lover, and vice versa.”¹⁰ Through this mutual indwelling we have a kind of connaturality with God, and this connaturality with God allows us to judge rightly concerning divine things.¹¹ If we lose the virtue of charity, necessarily we lose this connaturality with God, and so also we lose this divine gift of wisdom. Because charity is incompatible with mortal sin,¹² therefore this divine gift of wisdom is incompatible with mortal sin.¹³ So for Aquinas, all who have sanctifying grace have this divine gift of wisdom,¹⁴ by which they are guided in their actions not only by the natural light of reason, but also by the Divine light visible to them through their connaturality with God on account of the mutual indwelling that arises from the supernatural virtue of charity.

Sin Causes a Stain on the Soul

How then does the loss of the refulgence of both the light of natural reason and the Divine light produce a stain in the soul? Aquinas writes:

Now, when the soul cleaves to things by love, there is a kind of contact in the soul: and when man sins, he cleaves to certain things, against the light of reason and of the Divine law, as shown above (Question 71, Article 6). Wherefore the loss of comeliness occasioned by this contact, is metaphorically called a stain on the soul [macula animae].³

When a person sins, he turns away both from reason and from the Divine law. Aquinas explains that there are two rules or standards by which the human will is measured: “one is proximate and homogeneous, viz. the human reason; the other is the first rule, viz. the eternal law, which is God’s reason, so to speak.”¹⁵ By turning away from both of these lights, and loving something inordinately, a kind of stain in the soul results, as he explains:

[T]he act of the will consists in a movement towards things themselves, so that love attaches the soul to the thing loved [ita quod amor conglutinat animam rei amatae]. Thus it is that the soul is stained, when it cleaves inordinately [quando inordinate inhaeret], according to Hosea 9:10: “They . . . became abominable as those things were which they loved.”¹⁶

We know that a man cannot have two ultimate masters. (Matthew 6:24, Luke 16:13) This explains the sense in which we are not to love the world. The Apostle John writes, “Do not love the world nor the things in the world. If anyone loves the world, the love of the Father is not in him.” (1 John 2:15) Why is that? Love by its very nature attaches the soul to the thing loved. But love for something can be inordinate in two generically different ways: in itself contrary to love for God and neighbor, or compatible with love for God and neighbor but contrary to the perfect expression of love for God and neighbor.¹⁷ Inordinate love of the former sort is a love that prefers some created thing over God. But to love a creature more than one loves God is not to love God as God, but is rather to reject God as God. Therefore, when the soul cleaves inordinately to some created good in this way, that soul, in that particular way, turns away both from reason and from loving God. And by turning away from reason and from God, this soul loses the twofold refulgence of comeliness it possesses in the state of grace. That loss of comeliness is what Aquinas refers to as the stain in the soul.

Explanation of the Stain in the Soul

What exactly is the stain in the soul? Aquinas writes:

The stain is neither something positive in the soul, nor does it denote a pure privation: it denotes a privation of the soul’s brightness [nitoris] in relation to its cause, which is sin; wherefore diverse sins occasion diverse stains. It is like a shadow, which is the privation of light through the interposition of a body, and which varies according to the diversity of the interposed bodies.¹⁸

The stain is neither something positive nor a pure privation [privationem solam]. A pure or simple privation is a kind of corruption of being.¹⁹ But the stain in the soul is a complex [non simplex] privation, a privation of the soul’s comeliness in relation to the sin that caused this privation. In that respect, the stain in the soul is like a shadow that takes the shape of the object that is blocking the light. The manner in which the soul has turned away from reason and from God, in that very manner deprives the soul of its comeliness. Murder, for example, produces a different stain in the soul than does adultery or blasphemy, according as each by its inordinate love for something other than God causes a different sort of ‘shadow’ in the soul. The stain in the soul takes the ‘shape’ of the idol that is put in the place of God by that sin.

Here it is important to point out the significance of the distinction between mortal and venial sins, in relation to the stain in the soul.²⁰ According to Aquinas, mortal sin, but not venial sin, produces a stain in the soul. He writes:

Now, just as in the body there is a twofold comeliness, one resulting from the inward disposition of the members and colors, the other resulting from outward refulgence supervening, so too, in the soul, there is a twofold comeliness, one habitual and, so to speak, intrinsic, the other actual like an outward flash of light. Now venial sin is a hindrance to actual comeliness, but not to habitual comeliness, because it neither destroys nor diminishes the habit of charity and of the other virtues, as we shall show further on (II-II, 24, 10; 133, 1, ad 2), but only hinders their acts. On the other hand a stain denotes something permanent in the thing stained, wherefore it seems in the nature of a loss of habitual rather than of actual comeliness. Therefore, properly speaking, venial sin does not cause a stain in the soul. If, however, we find it stated anywhere that it does induce a stain, this is in a restricted sense, in so far as it hinders the comeliness that results from acts of virtue.²¹

Aquinas explains that the comeliness of the soul is twofold in another respect: intrinsic and extrinsic. The soul’s intrinsic comeliness is by the refulgence of its intrinsic dispositions. The soul’s extrinsic comeliness is by the refulgence of particular actions performed by this soul. Venial sin, by its very nature, does not destroy the habit of charity. Therefore, venial sin does not destroy the intrinsic comeliness of the soul, even though it hinders its extrinsic comeliness, by hindering charitable acts. But a stain, properly speaking, refers to something more permanent, not merely external or temporary. Therefore the stain on the soul refers to the loss of intrinsic comeliness rather than of extrinsic comeliness. But according to Aquinas one act of mortal sin destroys the virtue of charity in the soul.¹² Moreover, the loss of charity entails the loss of grace and supernatural wisdom.²² Therefore it follows that for Aquinas, while venial sin does not produce a stain in the soul, one act of mortal sin destroys the intrinsic comeliness of the soul, and thereby creates a stain in the soul.

The Stain in the Soul Persists after the Act of Sin is Past

According to Aquinas, the stain in the soul remains after the cessation of the sinful act. He writes:

The stain of sin remains in the soul even when the act of sin is past. The reason for this is that the stain, as stated above (Article 1), denotes a blemish in the brightness of the soul, on account of its withdrawing from the light of reason or of the Divine law. And therefore so long as man remains out of this light, the stain of sin remains in him: but as soon as, moved by grace, he returns to the Divine light and to the light of reason, the stain is removed. For although the act of sin ceases, whereby man withdrew from the light of reason and of the Divine law, man does not at once return to the state in which he was before, and it is necessary that his will should have a movement contrary to the previous movement. Thus if one man be parted from another on account of some kind of movement, he is not reunited to him as soon as the movement ceases, but he needs to draw nigh to him and to return by a contrary movement.²³

Aquinas explains that the stain in the soul is not caused fundamentally by the sinful action per se, but by the inordinate attachment of the will to something other than God. This inordinate attachment underlies the act and endures beyond it. So long as this inordinate attachment remains, the stain remains in the soul. But the cessation of the sinful act does not remove this inordinate attachment. Rather, this inordinate attachment remains in the will after the cessation of the sinful action, unless by a contrary movement the will is attached to God in love as its highest good. When the will turns to God in love, then the soul is reattached to God, because love attaches the soul to the thing loved, as explained above. Only then is the twofold refulgence of the natural light of reason and the Divine light restored to the soul, and the stain thus removed. But this movement of the will, turning from inordinate love of the world to love of God, is possible only by grace. Thus only by grace can the stain in the soul be removed.

In the next post in this series, I will examine what St. Thomas says about the third effect of sin: debt of punishment.

1. To read about this particular incident in the life of St. Thomas, see here. [↩]
2. Those three effects can be seen in the verse above. Peace requires the integrity of the various powers of the soul such that they are no longer at war with each other. This requires the healing of our corruption. To be found spotless requires the removal of the stain of sin. And to be found blameless entails no debt of payment to justice. [↩]
3. Summa Theologiae I-II Q.86 a.1 co. [↩] [↩]
4. Notice the twofold order: reason as the light to man’s natural end, and Divine wisdom and grace as the light to man’s supernatural end. [↩]
5. Summa Theologiae II-II Q.45 a.1 co. This gift of wisdom is one of the seven gifts of the Holy Spirit, as Aquinas explains in Summa Theologiae I-II Q.68. [↩]
6. Summa Theologiae II-II Q.45 a.2 co. [↩] [↩]
7. For Aquinas, God knows all things by a kind of connaturality, for He knows them all by knowing His own nature, in which all things live, and move, and have their being derivatively. Since necessarily the cause is greater than the effect, therefore God has a greater knowledge of creatures by knowing Himself than He would if He knew creatures only by exhaustively studying them. See Summa Theologiae I Q.14 a.5 [↩]
8. On the cogitative faculty, see Summa Theologiae I Q.78 a.4 [↩]
9. I have written about the natural love of friendship here. [↩]
10. Summa Theologiae I-II Q.28 a.2 [↩]
11. This connaturality with God, by way of charity, fits with what the Apostle Peter says in 2 Peter 1:4 concerning our becoming “partakers of the divine nature.” [γένησθε θείας κοινωνοὶ φύσεως] [↩]
12. Summa Theologiae II-II Q.24 a.12 [↩] [↩]
13. Summa Theologiae II-II Q.45 a.4 co. [↩]
14. Summa Theologiae II-II Q.45 a.5 [↩]
15. Summa Theologiae I-II Q.71 a.6 [↩]
16. Summa Theologiae I-II Q.86 a.1 ad 2 [↩]
17. See Summa Theologiae I-II Q.88 a.2 co. This distinction is what grounds the distinction between mortal and venial sins, respectively. [↩]
18. Summa Theologiae I-II Q.86 a.1 ad 3 [↩]
19. For an explanation of the distinction between the two kinds of privation: pure/simple privation, and complex privation, see Summa Theologiae I-II Q.73 a.2 co. [↩]
20. I will be discussing Aquinas’ explanation of the distinction between mortal and venial sin in the subsequent post on the debt of sin. [↩]
21. Summa Theologiae I-II Q.89 a.1 co. [↩]
22. Summa Theologiae II-II Q.45 a.4 [↩]
23. Summa Theologiae I-II Q.86 a.2 co. [↩]