Historic factors! But that is an expression of empiricists or ideologists who repeat Herder. Society is a complex whole or an organism according to the expression of some who waste their time in discussions over the value and the analogical use of this expression. This _complexus_ has formed itself and has changed several times. What is the explanation of this change? Even long before Feuerbach gave a final blow to the theological explanation of history (man makes religion and not religion man) the old Balzac[21] had made a satire of it by making men the puppets of God. And had not Vico already recognized that Providence does not act in history from without? And this same Vico, a century before Morgan, had he not reduced history to a process which man himself makes through successive experimentation consisting in the invention of language, religion, customs and laws? Had not Lessing affirmed that history is an education of the human race? Had not Rousseau seen that ideas are born from needs? Had not Saint Simon guessed when he did not lose himself in the distinction between organic and inorganic epochs the real genesis of the Third Estate, and did not his ideas translated into prose make of Augustin Thierry a reconstructor of historical research? In the first fifty years of this century and notably in the period from 1830 to 1850 the class struggles which the ancient historians and those of Italy during the Renaissance had described so clearly, instructed by the experience of these struggles in the narrow domain of their own urban republic had grown and had reached on both sides of the Channel greater proportions and an evidence always more palpable. Born in the midst of the great industry, illuminated by the recollection and by the study of the French Revolution they have become intuitively instructive because they found with more or less clearness and consciousness their actual and suggested expression in the programmes of the political parties: free exchange or tariffs on grain in England, and so on. The conception of history changed to the observer in France, on the right wing as on the left wing of the literary parties, from Guizot to Louis Blanc and to the modest Cabet. Sociology was the need of the time and if it sought in vain its theoretic expression in Auguste Comte, a belated scholastic, it found its artist in Balzac who was the actual inventor of class psychology. To put into the classes and into their frictions the real subject of history and the movement of this in their movement,--this is what was then on the point of being studied and discovered, and it was necessary to fix a theory of this in precise terms.