Thomas Aquinas

“ Further, actual sin has more of the character of guilt than original sin has. But actual sin does not change the nature of the body by subjecting it to some defect. Much less, therefore, does original sin. Therefore death and other bodily defects are not the result of sin. ”

“ Consequently as regards his form, incorruption is more natural to man than to other corruptible things. But since that very form has a matter composed of contraries, from the inclination of that matter there results corruptibility in the whole. In this respect man is naturally corruptible as regards the nature of his matter left to itself, but not as regards the nature of his form. ”

“ For supposing a man employs equal force in displacing two columns, it does not follow that the movements of the stones resting on them will be equal; but that one will move with greater velocity, which has the greater weight according to the property of its nature, to which it is left when the obstacle to its falling is removed. Accordingly, when original justice is removed, the nature of the human body is left to itself, so that according to diverse natural temperaments, some men's bodies are subject to more defects, some to fewer, although original sin is equal in all. ”

“ Wherefore in order to solve them, we must observe that the form of man which is the rational soul, in respect of its incorruptibility is adapted to its end, which is everlasting happiness: whereas the human body, which is corruptible, considered in respect of its nature, is, in a way, adapted to its form, and, in another way, it is not. ”

“ It would seem that weakness, ignorance, malice and concupiscence are not suitably reckoned as the wounds of nature consequent upon sin. For one same thing is not both effect and cause of the same thing. ”

“ Now from the very fact that thing becomes inclined to one of two contraries, its inclination to the other contrary must needs be diminished. Wherefore as sin is opposed to virtue, from the very fact that a man sins, there results a diminution of that good of nature, which is the inclination to virtue. ”

“ A thing's particular nature is its own power of action and self-preservation. And in respect of this nature, every corruption and defect is contrary to nature, as stated in De Coelo ii, text. 37, since this power tends to the being and preservation of the thing to which it belongs.
On the other hand, the universal nature is an active force in some universal principle of nature, for instance in some heavenly body; or again belonging to some superior substance, in which sense God is said by some to be "the Nature Who makes nature." ”

“ For there is a good belonging to the very substance of nature, which good has its mode, species and order, and is neither destroyed nor diminished by sin. There is again the good of the natural inclination, which also has its mode, species and order ”

“ Since, however, this same good of nature may be continually diminished by sin, some, in order to illustrate this, have made use of the example of a finite thing being diminished indefinitely, without being entirely destroyed. ”

“ In like manner the human body is the matter chosen by nature in respect of its being of a mixed temperament, in order that it may be most suitable as an organ of touch and of the other sensitive and motive powers. ”

“ Malice is not to be taken here as a sin, but as a certain proneness of the will to evil, according to the words of Gn. 8:21: "Man's senses are prone to evil from his youth" [*Vulgate: 'The imagination and thought of man's heart are prone to evil from his youth.'] . ”

“ Now if it were diminished in the first way, it would needs be entirely destroyed at last by the rational nature being entirely destroyed. Since, however, it is diminished on the part of the obstacle which is place against its attaining its term, it is evident that it can be diminished indefinitely, because obstacles can be placed indefinitely, inasmuch as man can go on indefinitely adding sin to sin: and yet it cannot be destroyed entirely, because the root of this inclination always remains. ”

“ Thus, a smith in order to make a knife, chooses a matter both hard and flexible, which can be sharpened so as to be useful for cutting, and in respect of this condition iron is a matter adapted for a knife: but that iron be breakable and inclined to rust, results from the natural disposition of iron, nor does the workman choose this in the iron, indeed he would do without it if he could: wherefore this disposition of matter is not adapted to the workman's intention, nor to the purpose of his art. ”

“ This force intends the good and the preservation of the universe, for which alternate generation and corruption in things are requisite: and in this respect corruption and defect in things are natural, not indeed as regards the inclination of the form which is the principle of being and perfection, but as regards the inclination of matter which is allotted proportionately to its particular form according to the discretion of the universal agent. ”

“ And although every form intends perpetual being as far as it can, yet no form of a corruptible being can achieve its own perpetuity, except the rational soul; for the reason that the latter is not entirely subject to matter, as other forms are ”

“ As stated above (Q [82] , A [3] , ad 1) , concupiscence is natural to man, in so far as it is subject to reason: whereas, in so far as it is goes beyond the bounds of reason, it is unnatural to man.
Reply to Objection 4: Speaking in a general way, every passion can be called a weakness, in so far as it weakens the soul's strength and clogs the reason. Bede, however, took weakness in the strict sense, as contrary to fortitude which pertains to the irascible. ”

“ For the Philosopher says (Phys. i, text. 37) that if from a finite magnitude a continual subtraction be made in the same quantity, it will at last be entirely destroyed, for instance if from any finite length I continue to subtract the length of a span. ”