That in Spirits there may be Sin, and how

AS there is an order in active causes, so also in final causes, requiring that the secondary end should be subordinate to the primary, as the secondary agent depends on the primary. Now every will naturally wishes that which is the proper good of the person willing, namely, his own perfect well-being; and the will cannot possibly will aught to the contrary of this. If we can find a voluntary agent, whose good is a final end, such as not to be contained under the order leading to any other end, but rather all other ends being contained in the order leading up to it, -- in such a voluntary agent there can be no fault of the will. Such a voluntary agent is God, whose being is sovereign goodness, which is the final end. In God then there can be no fault of the will. But in any other voluntary agent, whose proper good must necessarily be contained in the order leading to some other good, a sin of the will may occur, -- considering the agent as he is in his own nature.* In every voluntary agent there is a natural inclination to will and love his own perfect well-being, and that to such an extent that he cannot will the contrary. But a created agent has no natural endowment of so subordinating his own well-being to another end than himself as to be incapable of swerving from that end: for the higher end does not belong to the creature's own nature, but to a superior nature.* It is left therefore to the decision of his own will to subordinate his proper well-being to a higher end. Sin therefore might have found place in the will of a pure spirit in this way, -- that he did not refer his own good and well-being to the final end, but made that good his end and adhered to it accordingly. And because rules of conduct necessarily are taken from the end in view, it followed as a matter of course that the said spirit arranged his other elections according to that same object (ex re ipsa) in which he had placed his last end. Hence his will was not regulated by any higher will, a position of independence proper to God alone. In this sense we must understand the saying that he aimed at equality with God [cf. Isai. xiv, 13], not that he ever expected his goodness to equal the divine goodness: such a thought could never have occurred to his mind. But to wish to rule others, and not to have one's own will ruled by any superior, is to wish to be in power and cease to be a subject; and that is the sin of pride. Hence it is aptly said that the first sin that a spirit committed was pride. But because once error has been committed in regard to a first principle, a varied and manifold course of error is bound to ensue, so from the spirit's first inordination of will there followed manifold other sin in his will, such as hatred of God for withstanding his pride and justly chastising his offence, envy against man, and the like.

Further we may note that when any one's proper good is subordinate to several higher powers, it is open to a voluntary agent to withdraw himself from his subordination to one superior, and not relinquish his subordination to another, be that other the superior or the inferior of the first. Thus a soldier, being subordinate at once to the king and to the general of the army, may direct his will to the good of the general and not to the good of the king, or the other way about. If the general withdraws from his allegiance to the king, the will of the soldier, withdrawing from the will of the general and directing his affection to the king, will be good; and the will of the soldier, following the general's will against the will of the king, will be evil. Now not only are pure spirits subordinate to God, but also one of them is subordinate to another from first to last (B. II, Chap. XCV). And because in any voluntary agent, short of God, there may be sin in his will, if we consider him as left to his own nature, possibly one of the higher angels, or even the very highest of all, committed a sin in his will. And this is probable enough, that the sinner was highest of them all: for he would not have made his own good estate the final end of his acquiescence, had not his goodness been very perfect. Some of the lower angels then of their own will may have subordinated their good to [thrown in their lot with] that leader, and so have withdrawn their allegiance from God, and sinned as he did: while others, observing due regard to God in the motion of their will, rightly withdrew from their subordination to the sinner, although he was higher than they in the order of nature.

This is the difference between man and a pure spirit, that in the one being of man there are several appetitive faculties, one subordinate to another: this is not the case in pure spirits, although one of them is under another. But in man, however the inferior appetite may swerve from due subordination, any sin that occurs occurs in his will. As then it would be a sin in pure spirits for any inferior amongst them to swerve from due subordination to a superior, while that superior remained in subordination to God; so in the one person of man sin may occur in two ways: in one way by the human will not subordinating its own good to God, and that sin man has in common with the pure spirit; in another way by the good of the lower appetite not being regulated according to the higher, as when the pleasures of the flesh, to which the concupiscible appetite tends, are willed not in accordance with reason; and this sin does not occur in pure spirits.*

3.107 : That the Subsistent Intelligence, whose aid is employed in Magic, is not Evil by Nature
3.108, 110 : Arguments seeming to prove that Sin is impossible to Spirits, with Solutions of the same