The deductions and the combinations of the historians of economics, or of those who relate history in general, availing themselves of the guiding thread of economic phenomena, are not always so plausible or so conclusive, that one does not feel the need of saying to them: All this must be taken back and worked over. But that which is undoubted is the fact that in this present time all writing of history tends to become a science, or, better, a social discipline; and when that movement, now uncertain and multiform, shall be accomplished, the efforts of the scholars and inquirers will lead inevitably to the acceptance of economic materialism. By this incidence of efforts and of scientific labors, which start from points so opposite, the materialistic conception of all history will end by penetrating men's minds as a definite conquest of thought; and this will finally take away from partisans and adversaries the attempt to speak _pro_ and _con_ as for partisan theses. Apart from the direct helps just enumerated, our doctrine has many indirect helps, so that it can profitably employ the results of many disciplines, in which by reason of the greater simplicity of the relations, it has been possible more easily to make the application of the genetic method. The typical case is furnished by glottology, and in a more special fashion by the study which has for its object the ancient languages. The application of historical materialism is certainly, hitherto, very far from that evidence and that clearness of _processus_ of analysis and of reconstruction. It would be consequently a vain attempt to try, at this moment, to write a summary of universal history, which should propose to develop all the varied forms of production in order to deduce from them afterwards all the rest of human activity, in a particular and circumstantial fashion. In the present state of knowledge, he who should try to give this _compendium_ of a new _Kulturgeschichte_ would do nothing but translate into economic phraseology the points of general orientation which, in other books, for example, in Hellwald, give it in Darwinian phraseology. It is a long step from the acceptance of the principle to its complete and particular application to the whole of a vast province of facts, or to a great succession of phenomena.