_Answ._ Yes, if it be no more than a promise to that person; because a man may give away his right; but if it be moreover a vow to God, or you intend to oblige yourself in point of veracity under the guilt of a lie if you do otherwise, these alter the case, and no person can herein disoblige you.
_Quest._ XXX. But what if the contract be bound by an oath, may another then release me?
_Answ._ Yes, if that oath did only tie you to perform your promise; and were no vow to God, which made him a party by dedicating any thing to him; for then the oath being but subservient to the promise, he that dischargeth you from the promise, dischargeth you also from the oath which bound you honestly to keep it.
_Quest._ XXXI. Am I bound by a promise when the cause or reason of it proveth a mistake?
_Answ._ If by the cause you mean only the extrinsical reasons which moved you to it, you may be obliged nevertheless for finding your mistake; only so far as the other was the culpable cause, (as is aforesaid,) he is bound to satisfy you; but if by the cause you mean the formal reason, which constituteth the contract, then the mistake may in some cases nullify it (of which enough before).
_Quest._ XXXII. What if a following accident make it more to my hurt than could be foreseen?
_Answ._ In some contracts it is supposed or expressed, that men do undertake to run the hazard; and then they must stand obliged. But in some contracts, it is rationally supposed that the parties intend to be free, if so great an alteration should fall out. But to give instances of both these cases would be too long a work.
_Quest._ XXXIII. What if something unexpectedly fall out, which maketh it injurious to a third person? I cannot sure be obliged to injure another.
_Answ._ If the case be the latter mentioned in the foregoing answer, you may be thus free; but if it be the former, (you being supposed to run the hazard, and secure the other party against all others,) then either you were indeed authorized to make this bargain, or not; if not, the third person may secure his right against the other; but if you were, then you must make satisfaction as you can to the third person. Yea, if you made a covenant without authority, you are obliged to save the other harmless, unless he knew your power to be doubtful, and did resolve to run the hazard.
_Quest._ XXXIV. What if something fall out which maketh the performance to be a sin?
_Answ._ You must not do it; but you must make the other satisfaction for all the loss which you were the cause of, unless he undertook to stand to the hazard of this also (explicitly or implicitly).
_Quest._ XXXV. Am I obliged if the other break covenant with me?
_Answ._ There are covenants which make relations (as between husband and wife, pastor and flock, rulers and subjects); and covenants which convey title to commodities, of which only I am here to speak. And in these there are some conditions which are essential to the covenant; if the other first break these conditions, you are disobliged. But there are other conditions which are not essential, but only necessary to some following benefit, whose non-performance will only forfeit that particular benefit; and there are conditions which are only undertaken subsequent duties, trusted on the honesty of the performer; and in these a failing doth not disoblige you. These latter are but improperly called conditions.
_Quest._ XXXVI. May I contract to perform a thing which I foresee is like to become impossible or sinful, before the time of performance come, though it be not so at present.
_Answ._ With all persons you must deal truly; and with just contractors openly; but with thieves, and murderers, and persecutors, you are not always bound to deal openly. This being premised, either your covenant is absolutely, This I will do, be it lawful or not, possible or impossible; and such a covenant is sin and folly: or it is conditional, This I will do, if it continue lawful, or possible: this condition (or rather exception) is still implied where it is not expressed, unless the contrary be expressed: therefore such a covenant is lawful with a robber with whom you are not bound to deal openly; because it is but the concealing from him the event which you foresee. As e. g. you have intelligence that a ship is lost at sea, or is like to be taken by pirates, which the robber expecteth shortly to come safe into the harbour: you may promise him to deliver up yourself his prisoner, when that ship cometh home. Or you know a person to be mortally sick, and will die before the next week; you may oblige yourself to marry or serve that person two months hence; for it is implied, if he or she be then alive. But with equal contractors, this is unlawful, with whom you are obliged not only to verity but to justice; as in the following cases will be further manifested.
_Tit. 3. Special Cases about Justice in Buying and Selling._