He believed, moreover, that natural law and positive law moved on almost constant and immutable parallel lines.
An attempt has been made to discover a natural law which will explain some at least of the miracles of Jesus.
In 1684 he commenced the career of professor of natural law at Leipzig, and soon attracted attention by his abilities, but particularly by his daring attack upon traditional prejudices, in theology and jurisprudence.
In this instance it may happen that the work of intelligence has only been mimicked in nature by blind forces which have accidentally produced organic life; and Mill is disposed to hold that if the evolution of species should be clearly established as due to natural law - if there has been no creation by special interposition - the argument falls to the ground and theism (apparently) is lost.
We are on firmer ground when simply describing the phenomena of primitive religion than when seeking to account for these in terms of natural law - in whatever sense the conception of natural law be applicable to the facts of the mental life of man.
But once again in his political writings he breaks away from empiricism in appealing to natural law - an intuitionalist or conceivably an idealist tradition.
The latter clearly distinguished between a positive law differing in different nations and a natural law based on a general and unchanging principle of human nature, and therefore obligatory upon all.
The connexion in Roman law between the ideas of equity, nature, natural law and the law common to all nations, and the influence of the Stoical philosophy on their development, are fully discussed in the third chapter of the work we have referred to.
Not to speak of the canonists, Thomas Aquinas gives natural law an important place; while Melancthon, drawing from Aquinas, gives it an entrance into Protestant thought.
The researches of Gregor Johann Mendel (1822-1884), abbot of the Augustinian monastery at Briinn, in connexion with peas and other plants, apparently indicate that there is a definite natural law at work in the production of hybrids.