interest of mankind that the law which is common to many nations, whether derived from nature, or instituted by divine command, or introduced by tacit consent and established by custom, should be treated of universally and methodically; but he wished more especially to reduce into a system the rules of intercourse which were practised between nations, instead of leaving the whole fabric to rest on general principles, the application of which might be maintained or denied by each nation in its transactions with its neighbours, according as it suited its convenience, or as the occasion might seem to warrant.
“I have employed,” he says, “by way of evidence of the existence of this law, the testimonies of philosophers, historians, poets, and in the last place, orators, not that implicit credit is to be given to them, for it is usual for them to serve their party, or their subject, or their cause, but because when many persons at different times and in different places affirm the same thing for certain, that circumstance ought to be ascribed to some general cause, which in the questions treated by us cannot be any other than a correct inference from some natural principles, or an universal consent. The former of these indicates the Law of Nature, the latter the Law of Nations, the difference between which must not be judged of from the language of their testimonies, for writers everywhere confound the terms ‘law of nature’ and ‘law of nations,’ but from the quality of the subject matter. For whatever cannot be deduced by clear reasoning from certain principles, and yet appears to be everywhere observed, must have had its origin in the free consent of all.” (Prolegomena, § 41.)
