But it was not given either to the ancient authors in the limited circle of their urban republics, nor to the writers of the Renaissance, always drifting between an imaginary return to antiquity and the need of grasping intellectually the new world in process of birth, to arrive at the precise analysis of the last elements from which society results, and which the incomparable genius of Aristotle did not see, and did not understand beyond the limits within which passes the life of the typical citizen. The investigation of the social structure, considered in its manners of origin and _processus_, became active and penetrating and took on multiform aspects in the seventeenth and eighteenth centuries, when economics took shape and when under the different names of "Natural Rights," "The Spirit of the Laws," or "The Social Contract," it was attempted to resolve into causes, into factors and into logical and psychological data, the multiform and often obscure spectacle of a life in which was preparing the greatest revolution ever known. These doctrines, whatever may have been the subjective intention and spirit of the authors--as in the contrasting cases of the conservative Hobbes and the proletarian Rousseau--were all revolutionary in their substance and their effects. Under all of them is always found, as a stimulus and motive, the material and moral needs of a new age, which, by reason of historic conditions, were those of the bourgeoisie. Thus it was necessary to wage war in the name of liberty upon tradition, the Church, privileges, fixed classes, that is to say, the orders and conditions, and consequently upon the State which was or appeared to be their author, and then upon the special privileges of commerce, the arts, labor and science. And man was studied in an abstract fashion, that is to say, individuals taken separately, emancipated and delivered by a logical abstraction from their historic connection and from every social necessity: in the mind of many the concept of society was reduced to atoms, and it even seemed natural to the greatest number to believe that society is only the sum of the individuals composing it. The abstract categories of individual psychology sufficed for the explanation of all human facts; and this is how in all these systems, nothing is spoken of but fear, self-love, egoism, voluntary obedience, tendency toward happiness, the original goodness of man, the freedom of contract and of the moral consciousness, and of the moral instinct or sense, and also many other similar abstract and generic things, as if they were sufficient to explain history, and to create a new history out of its fragments.