But the socialism which had existed so far was just as incompatible with the materialistic conception of history as was the naturalistic French materialism with the dialectic and the modern discoveries in natural science. The then existing socialism criticised the prevailing capitalistic methods of production and their results but it could not explain them and thus could not match itself against them, it could only brush them on one side as being bad. But it was necessary to show, on the one hand, the capitalistic methods of production in their historical connection, and their necessity at a given historical epoch and therefore the necessity of their ultimate disappearance. On the other hand their inner character had to be explained and this was all the more concealed for criticism had up to then been chiefly engaged in pointing out the evil results flowing from them rather than in destroying the thing itself. This was made clear by the discovery of surplus value. It was shown that the appropriation of unpaid labor is the basis of the capitalistic mode of production and the robbery of the worker is carried out by its means; that the capitalist, although he buys the labor-force of the worker at the full value which it possesses in the market as a commodity, yet derives more from it than he has paid for it, and that in the last instance this surplus creates the total amount of value from which the capital steadily increasing in the hands of the capitalistic class is amassed. The phenomenon not only of capitalistic production but of the creation of capital has thus been explained. For these two great discoveries, the materialistic conception of history and the disclosure of the mystery of capitalistic production we must thank Marx. Granted these, socialism became a science, which thereupon had to busy itself in the working out of these ideas in their individual aspects and connections. Thus matters stood in the realm of theoretical socialism and the dead philosophy (of metaphysics Ed.) when Herr Eugene Duehring, with no slight impressement sprang up before the public and announced that he had accomplished a complete revolution in political economy and socialism. Let us now see what Herr Duehring promises and--how he keeps his promises. _II. What Herr Duehring Has to Say._ Up to now, the notable writings of Herr Duehring are his "Course of Philosophy," his "Course of Political and Social Science" and his "Critical History of Political Economy and Socialism." The first work is the one which particularly claims our attention.