10. When he or they in whom is the sovereign power of a commonwealth, are to ordain laws for the government and good order of the people, it is not possible they should comprehend all cases of controversy that may fall out, or perhaps any considerable diversity of them: but as time shall instruct them by the rising of new occasions, so are also laws from time to time to be ordained: and in such cases where no special law is made, the law of nature keepeth its place, and the magistrates ought to give sentence according thereunto, that is to say, according to natural reason. The constitutions therefore of the sovereign power, by which the liberty of nature is abridged, are written, because there is no other way to take notice of them; whereas the laws of nature are supposed to be written in men’s hearts. Written laws therefore are the constitutions of a commonwealth expressed; and unwritten, are the laws of natural reason. Custom of itself maketh no laws. Nevertheless when a sentence hath been once given, by them that judge by their natural reason, whether the same be right or wrong, it may attain to the vigour of a law; not because the like sentence hath of custom been given in the like case, but because the sovereign power is supposed tacitly to have approved such sentence for right, and thereby it cometh to be a law, and numbered amongst the written laws of the commonwealth. For if custom were sufficient to introduce a law, then it would be in the power of every one that is deputed to hear a cause, to make his errors laws. In the like manner, those laws that go under the title of _responsa prudentum_, that is to say, the opinions of lawyers, are not therefore laws, because _responsa prudentum_, but because they are admitted by the sovereign. And from this may be collected, that when there is a case of private contract between the sovereign and the subject, a precedent against reason shall not prejudice the cause of the sovereign; no precedent being made a law, but upon supposition that the same was reasonable from the beginning. And thus much concerning the elements and general grounds of laws natural and politic. As for the law of nations, it is the same with the law of nature. For that which is the law of nature between man and man, before the constitution of commonwealth, is the law of nations between sovereign and sovereign, after. ------------------------------------------------------------------------ OF LIBERTY AND NECESSITY: A TREATISE, WHEREIN ALL CONTROVERSY CONCERNING PREDESTINATION, ELECTION, FREE-WILL, GRACE, MERITS, REPROBATION, &c. IS FULLY DECIDED AND CLEARED. IN ANSWER TO A TREATISE WRITTEN BY THE BISHOP OF LONDONDERRY, ON THE SAME SUBJECT.