_Quest._ But will every change disoblige us? If not, what change must it be? seeing casuists use to put it as a condition in general, _rebus sic stantibus_. _Answ._ No: it is not every change of things that disobligeth us from the bonds of a vow. For then vows were of no considerable signification. But, 1. If the very matter that was vowed, or about which the vow was, do cease, _cessante materia, cessat obligatio_:[65] as if I promise to teach a pupil, I am disobliged when he is dead. If I promise to pay so much money in gold, and the king should forbid gold and change his coin, I am not obliged to it. 2. _Cessante termino vel correlato, cessat obligatio_: If the party die to whom I am bound, my personal obligation ceaseth. And so the conjugal bond ceaseth at death, and civil bonds by civil death. 3. _Cessante fine, cessat obligatio_: If the use and end wholly cease, my obligation, which was only to that use and end, ceaseth. As if a physician promise to give physic for nothing for the cure of the plague, to all the poor of the city; when the plague ceaseth, his end, and so his obligation, ceaseth. 4. _Cessante persona naturali relata, cessat obligatio personalis_: When the natural person dieth, the obligation ceaseth. I cannot be obliged to do that when I am dead, which is proper to the living. The subject of the obligation ceasing, the accidents must cease. 5. _Cessante relatione vel persona civili, cessat obligatio talis, qua talis_: The obligation which lay on a person in any relation merely as such, doth cease when that relation ceaseth. A king is not bound to govern or protect his subjects if they traitorously depose him, or if he cast them off, and take another kingdom (as when Henry III. of France left the kingdom of Poland): nor are subjects bound to allegiance and obedience to him that is not indeed their king. A judge, or justice, or constable, or tutor, is no longer bound by his oath to do the offices of these relations, than he continueth in the relation. A divorced wife is not bound by her conjugal vow to her husband as before, nor masters and servants, when their relations cease; nor a soldier to his general by his military sacrament, when the army is disbanded, or he is cashiered or dismissed.
_Rule_ III. No vows or promises of our own can dissolve the obligation laid upon us by the law of God. For we have no co-ordinate, much less superior authority over ourselves; our self-obligations are but for the furthering of our obedience.
_Rule_ IV. Therefore no vows can disoblige a man from any present duty, nor justify him in the committing of any sin. Vows are to engage us to God, and not against him: if the matter which we vow be evil, it is a sin to vow it, and a sin to do it upon pretence of a vow. Sin is no acceptable sacrifice to God.