47. The purport of the commandment is, since God, who is truth, abhors falsehood, we must cultivate unfeigned truth towards each other. The sum, therefore, will be, that we must not by calumnies and false accusations injure our neighbour's name, or by falsehood impair his fortunes; in fine, that we must not injure any one from petulance, or a love of evil-speaking. To this prohibition corresponds the command, that we must faithfully assist every one, as far as in us lies, in asserting the truth, for the maintenance of his good name and his estate. The Lord seems to have intended to explain the commandment in these words: "Thou shalt not raise a false report: put not thine hand with the wicked to be an unrighteous witness." "Keep thee far from a false matter," (Exod. 23:1, 7). In another passage, he not only prohibits that species of falsehood which consists in acting the part of tale-bearers among the people, but says, "Neither shalt thou stand against the blood of thy neighbour," (Lev. 19:16). Both transgressions are distinctly prohibited. Indeed, there can be no doubt, that as in the previous commandment he prohibited cruelty unchastity, and avarice, so here he prohibits falsehood, which consists of the two parts to which we have adverted. By malignant or vicious detraction, we sin against our neighbour's good name: by lying, sometimes even by casting a slur upon him, we injure him in his estate. It makes no difference whether you suppose that formal and judicial testimony is here intended, or the ordinary testimony which is given in private conversation. For we must always recur to the consideration, that for each kind of transgression one species is set forth by way of example, that to it the others may be referred, and that the species chiefly selected, is that in which the turpitude of the transgression is most apparent. It seems proper, however, to extend it more generally to calumny and sinister insinuations by which our neighbours are unjustly aggrieved. For falsehood in a court of justice is always accompanied with perjury. But against perjury, in so far as it profanes and violates the name of God, there is a sufficient provision in the third commandment. Hence the legitimate observance of this precept consists in employing the tongue in the maintenance of truth, so as to promote both the good name and the prosperity of our neighbour. The equity of this is perfectly clear. For if a good name is more precious than riches, a man, in being robbed of his good name, is no less injured than if he were robbed of his goods; while, in the latter case, false testimony is sometimes not less injurious than rapine committed by the hand.
48. And yet it is strange, with what supine security men everywhere sin in this respect. Indeed, very few are found who do not notoriously labour under this disease: such is the envenomed delight we take both in prying into and exposing our neighbour's faults. Let us not imagine it is a sufficient excuse to say that on many occasions our statements are not false. He who forbids us to defame our neighbour's reputation by falsehood, desires us to keep it untarnished in so far as truth will permit. Though the commandment is only directed against falsehood, it intimates that the preservation of our neighbour's good name is recommended. It ought to be a sufficient inducement to us to guard our neighbour's good name, that God takes an interest in it. Wherefore, evil-speaking in general is undoubtedly condemned. Moreover, by evil-speaking, we understand not the rebuke which is administered with a view of correcting; not accusation or judicial decision, by which evil is sought to be remedied; not public censure, which tends to strike terror into other offenders; not the disclosure made to those whose safety depends on being forewarned, lest unawares they should be brought into danger, but the odious crimination which springs from a malicious and petulant love of slander. Nay, the commandment extends so far as to include that scurrilous affected urbanity, instinct with invective, by which the failings of others, under an appearance of sportiveness, are bitterly assailed, as some are wont to do, who court the praise of wit, though it should call forth a blush, or inflict a bitter pang. By petulance of this description, our brethren are sometimes grievously wounded. But if we turn our eye to the Lawgiver, whose just authority extends over the ears and the mind, as well as the tongue, we cannot fail to perceive that eagerness to listen to slander, and an unbecoming proneness to censorious judgments are here forbidden. It were absurd to suppose that God hates the disease of evil-speaking in the tongue, and yet disapproves not of its malignity in the mind. Wherefore, if the true fear and love of God dwell in us, we must endeavour, as far as is lawful and expedient, and as far as charity admits, neither to listen nor give utterance to bitter and acrimonious charges, nor rashly entertain sinister suspicions. As just interpreters of the words and the actions of other men, let us candidly maintain the honour due to them by our judgment, our ear, and our tongue.