That there was no law of nature that man should love mankind, and that, if there had been any love on earth hitherto, it was not owing to a natural law, but simply because men have believed in immortality.
Ivan Fyodorovitch added in parenthesis that the whole natural law lies in that faith, and that if you were to destroy in mankind the belief in immortality, not only love but every living force maintaining the life of the world would at once be dried up.
There are no more uses of "natural law" in the book.
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There is much disagreement about natural laws, but everyone can agree that the concept was vital to the creation of the Bill of Rights.
All this was inviolable, like any set of natural laws.