19. The fourteenth precept of the law of nature is, _that safety must be assured to the mediators for peace_. For the reason which commands the end, commands also the means necessary to the end. But the first dictate of reason is peace; all the rest are means to obtain it, and without which peace cannot be had. But neither can peace be had without mediation, nor mediation without safety. It is therefore a dictate of reason, that is, a law of nature, that we must give all security to the mediators for peace. [Sidenote: The fifteenth law, of appointing an umpire.] 20. Furthermore because, although men should agree to make all these and whatsoever other laws of nature, and should endeavour to keep them, yet doubts and controversies would daily arise concerning the application of them unto their actions, to wit, whether what was done were against the law or not, which we call the question of right; whence will follow a fight between parties, either-sides supposing themselves wronged: it is therefore necessary to the preservation of peace, because in this case no other fit remedy can possibly be thought on, that both the disagreeing parties refer the matter unto some third, and oblige themselves by mutual compacts to stand to his judgment in deciding the controversy. And he to whom they thus refer themselves, is called an arbiter. It is therefore the fifteenth precept of the natural law, _that both parties disputing concerning the matter of right, submit themselves unto the opinion and judgment of some third_. [Sidenote: The sixteenth law, that no man be judge in his own cause.] 21. But from this ground, that an arbiter or judge is chosen by the differing parties to determine the controversy, we gather that the arbiter must not be one of the parties. For every man is presumed to seek what is good for himself naturally, and what is just only for peace sake and accidentally; and therefore cannot observe that same equality commanded by the law of nature, so exactly as a third man would do. It is therefore in the sixteenth place contained in the law of nature, _that no man must be judge or arbiter in his own cause_. [Sidenote: The seventeenth law, that arbiters must be without all hope of reward from the parties whose cause is to be judged.] 22. From the same ground follows in the seventeenth place, _that no man must be judge, who propounds unto himself any hope of profit or glory from the victory of either part_: for the like reason sways here, as in the foregoing law. [Sidenote: The eighteenth law, of witnesses.]