The bourgeois society is the most highly developed and most highly differentiated historical organization of production. The categories which serve as the expression of its conditions and the comprehension of its own organization enable it at the same time to gain an insight into the organization and the conditions of production which had prevailed under all the past forms of society, on the ruins and constituent elements of which it has arisen, and of which it still drags along some unsurmounted remnants, while what had formerly been mere intimation has now developed to complete significance. The anatomy of the human being is the key to the anatomy of the ape. But the intimations of a higher animal in lower ones can be understood only if the animal of the higher order is already known. The bourgeois economy furnishes a key to ancient economy, etc. This is, however, by no means true of the method of those economists who blot out all historical differences and see the bourgeois form in all forms of society. One can understand the nature of tribute, tithes, etc., after one has learned the nature of rent. But they must not be considered identical. Since, furthermore, bourgeois society is but a form resulting from the development of antagonistic elements, some relations belonging to earlier forms of society are frequently to be found in it but in a crippled state or as a travesty of their former self, as e. g. communal property. While it may be said, therefore, that the categories of bourgeois economy contain what is true of all other forms of society, the statement is to be taken _cum grano salis_. They may contain these in a developed, or crippled, or caricatured form, but always essentially different. The so-called historical development amounts in the last analysis to this, that the last form considers its predecessors as stages leading up to itself and perceives them always one-sidedly, since it is very seldom and only under certain conditions that it is capable of self-criticism; of course, we do not speak here of such historical periods which appear to their own contemporaries as periods of decay. The Christian religion became capable to assist us to an objective view of past mythologies as soon as it was ready for self-criticism to a certain extent, _dynamei_ so-to-say. In the same way bourgeois political economy first came to understand the feudal, the ancient, and the oriental societies as soon as the self-criticism of the bourgeois society had commenced. So far as bourgeois political economy has not gone into the mythology of purely (?) identifying the bourgeois system with the past, its criticism of the feudal system against which it still had to wage war resembled Christian criticism of the heathen religions or Protestant criticism of Catholicism.