Herr Duehring is therefore a mystifier when he asserts that the negation of the negation was an analogy made by Hegel derived from religion and built up on the story of the Fall and the Redemption. Men thought dialectically a long time before they knew what the dialectic really was, just as they spoke prose a long time before the term "prose" was used. The law of the negation of the negation which operates in history and which until it is once learned goes on in our brains unconsciously to ourselves, was first clearly formulated by Hegel, and if Herr Duehring desires to employ it in secret but cannot stand the name, he should discover a better name. But if he insist on expelling it from the processes of thought, he must first be good enough to expel it from nature and from history, and find a system of mathematics in which --a multiplied by --a does not give us + a^2 and where the differential and integral calculus are both forbidden by law. _Conclusion._ In this short section Engels leaves the general discussion in order to again pay his respects to the shortcomings and deficiencies of Herr Duehring. The matter possesses no general interest for Engels merely teases his opponent upon the magnificence of his claims and the slightness of his performances. PART II CHAPTER VIII POLITICAL ECONOMY _I. Objects and Methods._ Political economy is, in the widest sense, the science of the laws controlling the production and exchange of the material necessities of life in human society. Production and exchange are two entirely different functions. Production may exist without exchange, exchange--since there can only be exchange of products--cannot exist without production. Each of the two social functions is controlled by entirely different external influences and thus has, generally speaking, its own peculiar laws. But on the other hand they become so mutually involved at a given time and react one upon the other that they might be designated the abscisses and ordinates of the economic curve.