Bear in mind that we are here dealing for the moment solely with lawful swearing.  There are such things as imprecation, blasphemy, and general profanity, of which there will be question later, and which have this in common with the oath, that they call on the name of God; the difference is the same that exists between bad and good, right and wrong.  These must therefore be clearly distinguished from religious and legal swearing.

There is also a difference between a religious and a legal oath.  The religious oath is content with searching the conscience in order to verify the sincerity or insincerity of the swearer.  If one really intends to swear by God to a certain statement, and employs certain words to express his intention, he is considered religiously to have taken an oath.  If he pronounces a formula that expresses an oath, without the intention of swearing, then he has sworn to nothing.  He has certainly committed a sin, but there is no oath.  Again, if a man does not believe in God, he cannot swear by Him; and in countries where God is repudiated, all attempts at administering oaths are vain and empty.  You cannot call, to attest the truth of your words, a being that does not exist, and for him who does not believe in God, He does not exist.

The purely legal oath considers the fact and supposes the intention.  If you swear without deliberation, then, with you lies the burden of proving it; since the law will allow it only on evidence and will hold you bound until such evidence is shown.  When a person is engaged in a serious affair, he is charitably supposed to know what he is talking about; if it happens that he does not, then so much the worse for him.  In the case of people who protest beforehand that they are infidels or agnostics, or who being sworn on the New Testament, disclaim all belief in Christ, there is nothing to be done, except it be to allow them to attest by the blood of a rooster or by the Great Horn Spoon.  Then, whatever way they swear, there is no harm done.

CHAPTER XXXVII.  OATHS.

The first quality of an oath is that it be true.  It is evident that every statement we make, whether simple or sworn, must be true.  If we affirm what we know to be false we lie, if we swear to what we know to be false, we perjure ourselves.  Perjury is a sacrilegious falsehood, and the first sin against the Second Commandment.

If, while firmly believing it to be true, what we swear to happens to be false, we are not guilty of perjury, for the simple reason that our moral certitude places us in good faith, and good faith guarantees us against offending.  The truth we proclaim under oath is relative not absolute, subjective rather than objective, that is to say, the statement we make is true as far as we are in a position to know.  All this holds good before the bar of conscience, but it may be otherwise in the courts where something more than personal convictions, something more akin to scientific knowledge, is required.