Summa summae S. Thomae, Tomus III

Note. A twofold fault is distinguished : one theological, the other juridical. Theological fault is formal sin before God, whether mortal or venial. Juridical fault is the omission of some diligence from which damage follows to another. Such an omission, I say, jurists call a fault, even if perchance it be not a fault before God, for example because it is either involuntary, or is not of such diligence as one is bound to employ. But if it be a voluntary omission of such diligence as one can and is bound to employ, it will be at once both a theological and a juridical fault.

Juridical fault is divided into gross, light, and lightest. Gross fault is the omission of the diligence which prudent men are accustomed to employ in such a case, in such a business; as if someone go out of the house without having closed the door of the inner room.

Light fault is the omission of the diligence which the more prudent are accustomed to employ; as if someone go out with the door of the room indeed closed, but not bolted.

Lightest fault is the omission of the diligence which the most prudent are accustomed to employ; as if someone did not try with his hand whether a closed and bolted door were well bolted.

It is asked, therefore, whether in simple damaging, in which no gain accrues to the damager, theological fault is required, or that he have sinned before God, in order that he be liable to restitution, or whether juridical fault suffices. Concerning which :

I say : No one, contract set aside, is bound to restitution by reason of damage inflicted before the sentence of the judge, unless he have admitted theological fault against commutative justice in inflicting the damage. This is the common teaching against Adrian and certain ancient authors.

Proof. The damager, in the case proposed, is not bound to restore by reason of a thing received ; because, as is supposed, he received nothing, nor has he been made richer by the damage : nor by reason of an unjust action ; for where there is no fault before God, the damaging action is not formally unjust : nor from positive law ; for none can be assigned outside of contract. Therefore from no heading is he bound to restore,

It is confirmed. If damaging merely materially unjust induced the obligation of restoring, it would follow that a madman, or one asleep, or one who damaged his neighbor by a mere chance event, would be held to restitution ; which no one admits.

Therefore, however much damage to another may follow from your act, if you have not truly sinned before God, either because you employed the due diligence, or because you omitted it through natural inadvertence or blameless forgetfulness, although it is called gross fault in law, you are not held to restore in the forum of conscience before the sentence of the judge.

And this is true even though the damager deal with a thing illicitly, provided it be not dangerous and as it were a way leading to damage, such that neither per se nor in the majority of cases does damage follow from it, nor could it have been foreseen in a human way as about to follow; because, although the cause is voluntary, it is nevertheless not voluntary as the cause of such damage, which could not be foreseen in a human way as about to follow from it. Hence, if while hunting in a prohibited place or time you kill a man, thinking invincibly that you are killing a wild beast, you are not held to restore on account of the homicide.

I said, « before the sentence of the judge ; » because the judge, where there is gross juridical fault, though there be no theological fault, through natural inadvertence or some other case, is accustomed to condemn the damager to restitution or rather to payment, or to the surrender of the animal, if the damage was inflicted through an animal, unless it be otherwise certainly evident that he is innocent. And the damager is held, more probably, to obey this sentence as just in the forum of conscience. For this sentence does not rest upon a false presumption, as certain ones think; because the judge condemns you not because he presumes you have sinned internally before God, but because you have sinned externally, that is, because you omitted the diligence which prudent men are accustomed to employ, on account of which juridical fault, though not theological, the laws decree the obligation of restoring, with the sentence of the judge supervening.

And indeed justly, both because gross juridical fault usually proceeds from theological fault, although the contrary sometimes occurs per accidens, and laws attend to what happens for the most part; and on account of the common good, namely that men be more attentive in guarding their own goods, and more cautious in avoiding damage to their neighbor.

[You will ask whether he is held to restitution who blamelessly placed the cause of the damage, if afterward he neglect to remove it.

I answer, affirmative ; because he who placed the efficacious cause of the damage, and does not retract it when he morally can, wills it virtually, and consequently becomes at that moment strictly, effectively and formally the unjust cause of the damage¹.

I said, « when he morally can, » that is, without great and proportionate inconvenience, as is commonly taught.]