Question Five of Chapter Ten of the Third Decade
On the causes why demons tempt human beings
It is asked what causes there are for demons thus to tempt, torment, and lie in wait for human beings.
It is answered that there is a fivefold cause why demons lie in wait for human beings.
The first is their malice, because, since they hold God in hatred, from their malice they seek to turn human beings away from the service of God as much as they can.
Just as one who is hostile to and hates someone seeks to turn that person’s subjects away from his obedience and reverence, so demons from malice seek to turn God’s servants away from his service, and especially the holier and better ones.
Hence Jerome says to Eustochium: “The devil does not seek unbelieving human beings, nor those who are outside and whose flesh the king cooks in a pot. He hastens to snatch Ahasuerus from the Church of Christ. According to Habakkuk, his foods are choice. He desires to overthrow Job, and after devouring Judas he seeks permission to sift the apostles.”
And in Job, chapter 40: “His food is choice, and he trusts that the Jordan will flow into his mouth”—that is, that he may devour those cleansed by baptism. Baptism had its origin in the Jordan, and therefore the baptized are signified by the Jordan.
The second cause is their pride with respect to divine power, which they endeavor to usurp. Just as God has good angels ministering to and attending him in determinate offices for the salvation of human beings, so demons, in attacking, wish to appear to have determinate ministers for themselves to attack human beings.
Therefore it is said near the end of Job: “He is king over all the children of pride.”
There is an example in the Lives of the Fathers concerning Satan, who was seen by a certain person to demand an account from his attendants—demons of an inferior rank—concerning the evils to which they had induced those tempted by them. He greatly commended and honored the one who had at last led a certain holy man dwelling in the desert, whom he had tempted for many years, to a fall through lust.
The third cause is envy. For demons, envying the salvation of human beings, strive to impede their progress through temptations.
Hence it is said in Wisdom 2: “But through the envy of the devil death entered into the world.”
And in cause 16, question 2, chapter Visis, it is said concerning the devil that he grieves greatly and blushes that human beings, constant though made from clay matter, retain on earth the charity which he was unable to have—that is, to preserve—in heaven, and because they ought to ascend there whence he descended.
Therefore Augustine says in The City of God: “Juno does not seem to have envied the Romans as greatly as demons envy the whole human race the eternal seats.”
And although demons know that their punishment is increased by the damnation of evil human beings whom they tempt from envy, just as the glory of angels increases from their incitement of human beings toward good, they nevertheless do not on this account cease to tempt human beings.
They are like the envious man of whom it is related that he asked for one of his eyes to be torn out so that both eyes might be torn out from his neighbor, whom he envied.
For it is said concerning a certain king that he promised two persons—an envious man and a greedy man—that he would do whatever they asked, but in such a way that the one who asked later would receive double.
When each delayed asking—the one moved by desire to possess a double good, and the other lest his companion possess more than he himself—the king finally ordered the envious man to ask first. He asked that one of his own eyes be torn out so that his companion might lose both. For he did not wish to ask for anything good, lest his companion possess double.
Thus demons tempt human beings from envy, although they are not ignorant that their own punishment will increase in the future from the damnation of human beings.
The fourth cause is the justice of God, which uses them as instruments and ministers for punishing human beings. Thus in this world a lying spirit was sent to punish Ahab, king of Israel, as is said at the end of 3 Kings; and in hell God uses them in the same manner for justice.
The fifth cause is the sloth of human beings, because they have lost their weapons.
For in Part IV of the Lives of the Fathers it is set down that, when a certain old man asked an old abbot why human beings and monks were vexed by demons, the old man answered: “Because they have lost their weapons”—that is, the virtues: penance, humility, obedience, and poverty.
These things are from Thomas, First Part, question 114, article 1, and Lord Antoninus, Archbishop of Florence, in the First Part of his Summa.
Addition
Since someone can also ask here why demons procure our evils with harm to themselves, it appears to me that three things must be said.
First, because it is a consolation to the wretched to have companions in their punishments.
Second, because they are led by such great envy that they do not see what they are doing and do not take good counsel for themselves.
Third, because they have been made so evil a tree that they cannot produce anything except evil fruits.