Concerning the Ten Commandments, which are the Heads of the Law (91-95)

If you know it not you are an atheist, and atheism is the beginning of all iniquity, and, in addition to your atheism, you are also adding the wickedness of an oath, by swearing by him who in your opinion is not attending to you, nor paying any regard to human affairs.

But if you are well assured that he does exert his providence in respect of such matters, still you are not free from the charge of excessive impiety, saying to God, if not with your mouth and tongue, still at all events with your conscience: Bear false witness for me, aid me in my wickedness, assist me in my impiety. I have but one hope of preserving a fair reputation among men, namely by concealing the truth; be thou wicked for another’s sake, you who are the better, for the sake of one who is worse; you who are God, the most excellent of all beings, for the sake of a man, and that too a wicked one.

But there are also some people who, without any idea of acquiring gain, do from a bad habit incessantly and inconsiderately swear upon every occasion, even when there is nothing at all about which any doubt is raised, as if they were desirous to fill up the deficiency of their argument with oaths, as if it would not be better to cut their conversation short, or I might rather say to utter nothing at all, but to preserve entire silence, for from a frequency of oaths arises a habit of perjury and impiety.

On which account the man who is going to take an oath ought to investigate everything with care and exceeding accuracy, considering whether the subject is of serious importance, and whether it has really taken place, and whether, if it has, he has comprehended it properly; and considering himself, also, whether he is pure in soul, and body, and tongue, having the first free from all violation of the law, the second from all defilement, and the last from all blasphemy.

For it is an impiety for any disgraceful words to be uttered by that mouth by which the most sacred name is also mentioned.

Let him also consider whether the place and the time are suitable; for before now I have known

And let him who pays but little heed to what has been said here know, in the first place, that he is impure and defiled; and, in the second place, that the most terrible punishments are constantly lying in wait for him; that justice who keeps her eye upon all human affairs, being implacable and inflexible towards all enormities of such a character; and, when she does not think fit to inflict her punishments at once, still exacting satisfaction with abundant usury whenever the opportunity seems to offer in combination with the general advantage. .