[T]he critique of economics could .. , be exercised in two ways: historically or logically …. History moves often in leaps and bounds and in a zigzag line, and as this would have to be followed throughout, it would mean not only that a considerable amount of material of slight importance would have to be included, but also that the train of thought would frequently have to be interrupted; it would, moreover, be impossible to write the history of economy without that of bourgeois society, and the task would thus become immense, because of the absence of all preliminary studies. The logical method of approach was therefore the only suitable one. This, however, is indeed nothing but the historical method, only stripped of the historical form and diverting chance occurrences …. [W]ith this method the logical exposi- tion need by no means be confined to the purely abstract sphere. On the contra?, it requires historical illustration and continuous contact with reality.