Nicene and Post-Nicene Fathers, Vol. III:
Moral Treatises of St. Augustin: Section 25

25. For first to be eschewed is that capital lie and far to be fled from, which is done in doctrine of religion; to which lie a man ought by no consideration to be induced. The second, that he should hurt some man unjustly: which is such that it profits no man and hurts some man. The third, which so profits one as to hurt another, but not in corporal defilement. The fourth, that which is done through only lust of lying and deceiving, which is an unmixed lie. The fifth, what is done with desire of pleasing by agreeableness in talk. All these being utterly eschewed and rejected, there follows a sixth sort which at once hurts nobody and helps somebody; as when, if a person’s money is to be unjustly taken from him, one who knows where the money is, should say that he does not know, by whomsoever the question be put. The seventh, which hurts none and profits some: except if a judge interrogate: as when, not wishing to betray a man who is sought for to be put to death, one should lie; not only a just and innocent, but also a culprit; because it belongs to Christian discipline neither to despair of any man’s amendment, nor to bar the way of repentance against any. Of which two sorts, which are wont to be attended with great controversy, we have sufficiently treated, and have shown what was our judgment; that by taking the consequences, which are honorably and bravely borne, these kinds also should be eschewed by brave and faithful and truthful men and women. The eighth sort of lie is that which hurts no man, and does good in the preserving somebody from corporal defilement, at least that defilement which we have mentioned above. For even to eat with unwashen hands the Jews thought defilement. Or if a person think this also a defilement, yet not such that a lie ought to be told to avoid it. But if the lie be such as to do an injury to any man, even though it screen a man from that uncleanness which all men abhor and detest; whether a lie of this kind may be told provided the injury done by the lie be such as consists not in that sort of uncleanness with which we are now concerned, is another question: for here the question is no longer about lying, but it is asked whether an injury ought to be done to any man, even otherwise than by a lie, that the said defilement may be warded off from another. Which I should by no means think: though the case proposed be the slightest wrongs, as that which I mentioned above, about a single measure of wheat; and though it be very embarrassing whether it be our duty not to do even such an injury to any man, if thereby another may be defended or screened from a lustful outrage upon his person. But, as I said, this is another question: at present let us go on with what we have taken in hand: whether a lie ought to be told, if even the inevitable condition be proposed that we either do this, or suffer the deed of lust or p. 470 some execrable pollution; even though by lying we do no man harm.