For the question is not of promises mutual, where there is no security of performance on either side; as when there is no civil power erected over the parties promising; for such promises are no covenants: but either where one of the parties has performed already; or where there is a power to make him perform; there is the question whether it be against reason, that is, against the benefit of the other to perform, or not. And I say it is not against reason. For the manifestation whereof, we are to consider; first, that when a man doth a thing, which notwithstanding any thing can be foreseen, and reckoned on, tendeth to his own destruction, howsoever some accident which he could not expect, arriving may turn it to his benefit; yet such events do not make it reasonably or wisely done. Secondly, that in a condition of war, wherein every man to every man, for want of a common power to keep them all in awe, is an enemy, there is no man who can hope by his own strength, or wit, to defend himself from destruction, without the help of confederates; where every one expects the same defence by the confederation, that any one else does: and therefore he which declares he thinks it reason to deceive those that help him, can in reason expect no other means of safety, than what can be had from his own single power. He therefore that breaketh his covenant, and consequently declareth that he thinks he may with reason do so, cannot be received into any society, that unite themselves for peace and defence, but by the error of them that receive him; nor when he is received, be retained in it, without seeing the danger of their error; which errors a man cannot reasonably reckon upon as the means of his security: and therefore if he be left, or cast out of society, he perisheth; and if he live in society, it is by the errors of other men, which he could not foresee, nor reckon upon; and consequently against the reason of his preservation; and so, as all men that contribute not to his destruction, forbear him only out of ignorance of what is good for themselves. As for the instance of gaining the secure and perpetual felicity of heaven, by any way; it is frivolous: there being but one way imaginable; and that is not breaking, but keeping of covenant. And for the other instance of attaining sovereignty by rebellion; it is manifest, that though the event follow, yet because it cannot reasonably be expected, but rather the contrary; and because by gaining it so, others are taught to gain the same in like manner, the attempt thereof is against reason. Justice therefore, that is to say, keeping of covenant, is a rule of reason, by which we are forbidden to do any thing destructive to our life; and consequently a law of nature.