“Marx was, and is, the only one who could undertake the work of extracting from the Hegelian logic, the kernel which comprises Hegel’s real discoveries in this sphere, and to reconstruct the dialectical method, divested of its idealistic trappings, in the simple shape in which it becomes the only true form of development of thought. The working out of the method which forms the foundation of Marx’s criticism of political economy we consider a result of hardly less importance than the basic materialist outlook itself. The criticism of economics, even according to the method acquired, could still be exercised in two ways: historically or logically. Since in history, as in its literary reflection, development as a whole also proceeds from the most simple to the more complex relations, the historical development of the literature of political economy provided a natural guiding thread with which  criticism could link up, and the economic categories as a whole would thereby appear in the same sequence as in the logical development. This form apparently has the advantage of greater clearness, since indeed it is the ‘actual’ development that is followed, but as a matter of fact it would thereby at most become more popular. History often proceeds by leaps and zigzags and it would thus have to be followed up everywhere, whereby not only would much material of minor importance have to be incorporated, but there would be much interruption of the chain of thought; furthermore, the history of economics could not be written without that of bourgeois society and this would make the task endless, since all preliminary work is lacking. The logical method of treatment was therefore, the only appropriate one. But this, as a matter of fact, is nothing else but the historical method, only divested of its historical form and disturbing fortuities. The chain of thought must begin with the same thing with which this history begins, and its further course will be nothing else but the reflection of the historical course in abstract and theoretically consistent form; a corrected reflection but corrected according to laws furnished by the real course of history itself, in that each, factor can be considered at the point of development of its full maturity, of its classic form. In this method we proceed from the first and simplest relation that historically and in fact confronts us; here, therefore, from the first economic relation to be found. We analyse this relation. Being a ‘relation’ of itself implies that it has two sides, ‘related to each other’. Each of these sides is considered by itself, which brings us to the way in which they behave to each other, their interaction. Contradictions will result which demand a solution. But as we are not considering here an abstract process of thought taking place solely in our heads, but a real process which actually took place at some particular time or is till taking place, these contradictions, too, will have developed in practice and will probably have found their solution. We shall trace the nature of this solution, and shall discover that it has been brought about by the establishment of a new relation whose two opposite sides we shall now have to develop, and so on” [F. Engels, ‘Karl Marx, A contribution to the critique of political economy,’, written by Engels during the first half of August 1859, Published in the newspaper ‘Das Volk’, August 6 and 20, 1859] [(in) Karl Marx Friedrich Engels, ‘Selected Works in Two Volumes. Volume I’, London, 1962]