It is useless to attempt at counterbalancing these essential difficulties by the metaphorical hypothesis, often equivocal, and after all of a purely analogical value, of the so-called social organism. It was necessary too that the mind should pass through even this hypothesis, which so shortly became phraseology pure and simple. It indeed prepares the way for the comprehension of the historic movement as springing from the laws immanent in society itself, and thereby excludes the arbitrary, the transcendental and the irrational. But the metaphor has no further application; and the particular, critical and circumstantial research into historic facts is the sole source of that concrete and positive knowledge which is necessary to the complete development of economic materialism.
Ideas do not fall from heaven, and nothing comes to us in a dream. The change in the ways of thinking, lately produced by the historic doctrine which we are here examining and commenting upon, takes place at first slowly and afterwards with an increasing rapidity, precisely in that period of human development, in which were realized the great politico-economic revolutions, that is to say, in that epoch which, considered in its political forms, is called liberal, but which, considered in its basis, by reason of the domination of capital over the proletarian mass, is the epoch of anarchical production. The change in ideas, even to the creation of new methods of conception, has reflected little by little the experience of a new life. This, in the revolutions of the last two centuries, was little by little despoiled of the mythical, religious and mystical envelopes in proportion as it acquired the practical and precise consciousness of its immediate and direct conditions. Human thought, also, which sums up this life and theorizes upon it, has little by little been plundered of its theological and metaphysical hypotheses to take refuge finally in this prosaic assertion: in the interpretation of history we must limit ourselves to the objective co-ordination of the determining conditions and of the determined effects. The materialistic conception marks the culminating point of this new tendency in the investigation of the historic-social laws, in so far as it is not a particular case of a generic sociology, or of a generic philosophy of the State, of law, and of history, but the solution of all doubts and all uncertainties which accompany the other forms of philosophizing upon human affairs, and the beginning of their integral interpretation.