By means of this theory of understanding, dialectic materialism also furnishes the means for the solution of the riddles of the world (Weltraetsel). Not that it solves all these riddles; on the contrary, it says explicitly that this solution can be but the work of an ever advancing scientific research. But it solves them in so far as it deprives them of the character of a mysterious enigma and transforms them into a practical problem, the solution of which we are approaching by an infinite progression. Bourgeois thought cannot solve the riddles of the world. A few years after the first publication of Dietzgen's work, natural science in the person of Du Bois-Reymond acknowledged its incapacity by his "Ignorabimus:" "We shall never know." Proletarian philosophy, in solving the riddle of the human mind, gives us the assurance that there are no insoluble riddles before us. In conclusion, Dietzgen in this work indicates the principles of a new ethics. Starting with the understanding that the origin of the ideas of good and bad is found in the needs of man, and designating as really moral that which is generally useful, he logically discovers that the essence of modern morality rests in its class interests. At the same time, a relative justification is accorded to these temporary ethics, since they are the necessary products of definite social requirements. The link between man and nature is formed by the process of social production carried on for the satisfaction of man's material wants. So long as this link was a fetter, it bound man by a misapprehended supernatural ethics. But once the process of social labor is understood, regulated and controlled, then this fetter is dropped and the place of ethics is taken by a reasonable understanding of the general wants. ************