VI. If then there has not been a great gain in clearness of fundamental concepts, as regards this part of the subject, there has on the contrary been an indubitable advance in consciousness acquired as to the mutability of laws and as to the consequent contradictoriness of the idea of natural Rights. This, with its complement, the catalogue of innate natural and inalienable rights of man, had great success in the seventeenth century for political and social reasons, attaining its highest development in the century following. But it may be said that the doctrine of innate rights was liquidated by Kant in the _Metaphysic of Custom,_ when he wrote the proposition that liberty is the only original and innate rights, which belong to man through his very humanity,[38] at the very moment when it was most energetically affirmed in a practical form in the _Declaration of the Rights of Man._ In the system of Hegel the constructions of natural rights began to lose their rigidity; becoming indeed historical categories of Ethicity or _Sittlichkeit,_ determinations of the spirits of various peoples (_Volksgeister,_) which are in their turn determinations of the Absolute or of the Idea. Owing to this view (without taking into account his error of wishing to philosophize and to make dialectical what is historical and empirical), Hegel connected himself closely with the historical school of rights (Hugo, Savigny, etc.). This, notwithstanding the exaggeration by which he seemed to deny the value of the ideal demands made of rights, had the merit of shaking the old conception of natural rights. This has retained its place in treatises from that time onward in a more or less worm-eaten and unstable condition by the force of inertia; or it has been preserved by Catholic writers (by Rosmini not less than by the Padre Taparelli), whose conception is of necessity but little historical; or it has reappeared in those curious Catholics and anti-historians, the positivists (Spencer, Ardigò). But that natural rights are nothing but _new_ historical rights in the struggle of their becoming, is a conviction that has penetrated the general consciousness. [Sidenote: _The comparison between rights and language._]