It is not in the attempts contemporary with the infancy of society, or nearly so, that we are to look for the complete realization of the precepts of the natural law; for principles obey the rule laid down by Aristotle. “The nature of each thing is precisely that which constitutes its end; and when each being has attained its entire development, we say that that is its own proper nature.”(15) The ideas of natural law are purified in proportion as society grows enlightened and free; but the truth appears only successively in the phases it passes through. It allows us to grasp one aspect of itself after another, but does not surrender itself entirely, at any one moment, to the investigations of the historian or the jurisconsult. History and philosophy interpenetrate and complement one another. III. The two schools, that of philosophy and that of history have met in our day, in the field of law. Who is there that does not remember the great and noble contest carried on, about the beginning of this century, between two descendants of Frenchmen who had sought a refuge in Germany, and who united in their own persons, and in so marvelous a manner, the different aptitudes of the country they owed their origin to, and of the land that gave them birth,—between Thibaut and Savigny? It would be difficult to find a scientific question of a higher character, debated by champions more worthy to throw light upon it. The _Code Napoléon_ had appeared. It had, to use Rossi’s happy expression, transferred into law the social revolution produced by the destruction of privilege. It was the practical formula expressive of the conquests which had been made. The philosophy of the eighteenth century had previously inspired the Prussian Code. And yet, it was on the question of codification that this memorable controversy was carried on. The two principal combatants, while manfully battling, the one against the other, continued to hold each other in high esteem, and the profound study of law was developed in the midst of the _melée_. We cannot delay long on this subject, nor analyze the arguments advanced by Thibaut(16) and Savigny.(17) What interests us at present is not so much the question debated, as the intellectual movement to which it gave birth. Savigny sustained the ancient law, Thibaut attacked it. Numerous and distinguished jurisconsults ranged themselves on the one side and the other. A new school grew up which, with the most brilliant success, made law throw light on history and history on law. The application of the historical method to the study of law was productive of the most happy results.