To show how the materialistic conception of history arises precisely in given conditions, not as a personal and tentative opinion of two writers, but as the new conquest of thought by the inevitable suggestion of a new world which is in process of birth, that is to say the proletarian revolution, that was the object of my first essay, "In Memory of the Communist Manifesto." That is, to repeat, a new historic situation found its complement in its appropriate mental instrument. To imagine now that this intellectual production might have been realized at any time and at any place, would be to take absurdity for the ruling principle in research. To transport ideas arbitrarily from the basis and the historic conditions in which they arise to any other basis whatever, is like taking the irrational for the basis of reasoning. Why should one not fancy equally that the ancient city, in which arose Greek art and science and Roman law, remaining all the while an ancient democratic city, with slavery, might at the same time acquire and develop all the conditions of modern technique? Why not believe that the trade guild of the Middle Ages, remaining all the while on its inflexible mould, should take its way to the conquest of the world market without the conditions of unlimited competition, which actually began by its destruction and negation? Why not imagine a fief which, remaining a fief all the while, should become a factory producing commodities exclusively? Why could not Michel de Lando have written the Communist Manifesto? Why could we not also believe that the discoveries of modern science could have proceeded from the brains of men of no matter what other time and place, that is to say, before determined conditions had given rise to determined needs, and before repeated and accumulated experiences should have provided for the satisfaction of these needs?