The identity of the Decalogue with the eternal law of nature was maintained in both churches, but it was an open question whether the Decalogue, as such (that is, as a law given by Moses to the Israelites), is of perpetual obligation.
These positions, though Grotius's religious temper did not allow him to rely unreservedly upon them, yet, even in the partial application they find in his book, entitle him to the honour of being held the founder of the modern science of the law of nature and nations.
As a lawyer his greatest public efforts were his lectures (1799) at Lincoln's Inn on the law of nature and nations, of which the introductory discourse was published, and his eloquent defence (1803) of Jean Gabriel Peltier, a French refugee, tried at the instance of the French government for a libel against the first consul.
But his handling of it is clumsy and confused; and he does not make it sufficiently clear why the law of nature should be obeyed.
A pantheist may believe in Law of Nature and go no further; a theist who accepts Law of Nature has a large instalment of natural theology ready made to his hand; including an idealist, or else an intuitionalist, scheme of ethics.
It supplied them with an incentive to scientific research in archaeology and grammar; it penetrated jurisprudence until the belief in the ultimate identity of the jus gentium with the law of nature modified the praetor's edicts for centuries.
Now we know that spiritual unions, prompted originally by highstrung Christian idealism as to a religious fellowship transcending the law of nature in relation to sex, did exist between persons living under vows of celibacy during the 3rd century in particular, and not least in Syria (cf.
Indeed Locke seems to allow that the consent was at first tacit, and by anterior law of nature conditional on the beneficial purpose of the trust being realized.