text: 4. Of lies are many sorts, which indeed all, universally, we ought to hate. For there is no lie that is not contrary to truth. For, as light and darkness, piety and impiety, justice and iniquity, sin and right-doing, health and weakness, life and death, so are truth and a lie contrary the one to the other. Whence by how much we love the former, by so much ought we to hate the latter. Yet in truth there be some lies which to believe does no harm: although even by such sort of lie to wish to deceive, is hurtful to him that tells it, not to him that believes it. As though, if that brother, the servant of God, Fronto, in the information which he gave you, should (though far be the thought!) say some things falsely; he would have hurt himself assuredly, not you, although you, without iniquity of yours, had believed all, upon his telling it. Because, whether those things did so take place or not so, yet they have not anything, which if a person believe to have been so, though it were not so, he by the rule of truth and doctrine of eternal salvation should be judged worthy of blame. Whereas, if a person tell a lie which if any believe he will be an heretic against the doctrine of Christ, by so much is he who tells the lie more hurtful, by how much he that believes it is more miserable. See then, what manner of thing it is, if against the doctrine of Christ we shall tell a lie which whoever believes shall perish, in order that we may catch the enemies of the same doctrine, to the end we may bring them to the truth, while we recede from it; nay rather, when we catch liars by lying, teach worse lies. For it is one thing what they say when they lie, another when they are deceived. For, when they teach their heresy, they speak the things in which they are deceived; but when they say that they think what they do not think, or that they do not think what they do think, they say the things in which they lie. In that any believes them, what though he do not find them out, himself perishes not. For it is no receding from the catholic rule, if, when a heretic lyingly professes the catholic doctrines, one believes him to be a catholic: and therefore it is not pernicious to him; because he is mistaken in the mind of a man, of which, when latent, he cannot judge, not in the faith of God which it is his duty to keep safe planted within him. Moreover, when they teach their heresy, whoever shall believe them, in thinking it truth, will be partaker, as of their error, so of their damnation. So it comes to pass, that when they fable their nefarious dogmas in which they are with deadly error deceived, then whoever believes them is lost: whereas when we preach catholic dogmas, in which we hold the right faith, then if he shall believe, that man is found, whoever was lost. But when, they being Priscillianists, do, in order that they may not betray their venom, lyingly give themselves out to be of us; whoever of us believes them, even while they escape detection, himself perseveres a Catholic: we on the other hand, if, in order to attain to the discovery of them, we falsely give ourselves out for Priscillianists, because we shall praise their dogmas as though they were our own, whoever shall believe the same, will either be confirmed among them, or will be transferred to them in the meantime straightway: but what the coming hour may bring forth, whether they shall be afterwards set free therefrom by us when speaking true things, who were deceived by us when speaking false; and whether they will be willing to hear one teaching whom they have thus experienced telling a lie,who can know for certain? Who can be ignorant that this is uncertain? Whence it is gathered, that it is more pernicious, or to speak more mildly, that it is more perilous for Catholics to lie that they may catch heretics, than for heretics to lie that they may not be found out by Catholics. Because, whoever believes Catholics when they tell a lie to tempt people, is either made or confirmed a heretic; but whoever believes heretics when they tell a lie to conceal themselves, does not cease to be a Catholic. But that this may become more plain, let us propose some cases by way of example, and from those writings in preference which you have sent me to read.
  17. Wherefore, though there be indeed many ways in which latent heretics may be sought out, without vituperating the catholic faith or praising heretical impiety, yet if there were no other way at all of drawing out heretical impiety from its caverns, but that the catholic tongue should deviate from the straight path of truth; more tolerable were it that that should be hid, than that this should be precipitated; more tolerable that the foxes should lurk in their pits unseen, than for the sake of catching them the huntsmen should fall into the pit of blasphemy; more tolerable that the perfidy of Priscillianists should be covered with the veil of truth, than that the faith of Catholics, lest it should of lying Priscillianists be praised, should of believing Catholics be denied. For if lies, not of whatsoever kind, but blasphemous lies, are therefore just because they are committed with intent to detect hidden heretics; it will be possible at that rate, if they be commuted with the same intention, that there should be chaste adulteries. For put the case that of a number of lewd Priscillianists, some woman should cast her eye upon a catholic Joseph, and promise him that she will betray their hidden retreats if she obtain from him that he lie with her, and it be certain that if he consent unto her she will make good her promise: shall we judge that it ought to be done? Or shall we understand that by no means must such a price be paid in purchase of that kind of merchandise? Why then do we not rout out heretics, in order to their being caught, by the flesh committing lasciviousness in adultery, and yet think right to rout them out by a mouth committing fornication in blasphemy? For either it will be lawful to defend both the one and the other with equal reason, that these things be therefore said to be not unjust, because they were done with intention of finding out the unjust: or if sound doctrine wills not even for the sake of finding out heretics that we should have to do with unchaste women, albeit only in body, not in mind, assuredly not even for the sake of finding out heretics wills it that by us, albeit only in voice not in mind, either unclean heresy were preached, or the chaste Catholic Church blasphemed. Because even the very sovereignty of the mind, to which every inferior motion of the man ought to be obedient, will not lack deserved opprobrium, when a thing is done that ought not to be done, whether by member or by word. Although even when it is done by word, it is done by member: because the tongue is a member, by which the word is made; nor is any deed of ours by any member brought to the birth unless it is first conceived in the heart; or rather being by our inwardly thinking upon and consenting unto it already brought to the birth, it is brought forth abroad in our doing of it, by a member. It is therefore no excusing the mind from the deed, when anything is said to be done not after the purpose of the mind, which yet were not done, unless the mind decreed it to be done.