Your letter of the 3rd inst. was forwarded to me at Folkestone; but not having the book I needed I could not reply. Having returned on the 12th of the same month, I found such an amount of pressing work that only to-day am I able to write a few lines. Please excuse my delay. To your first question:- First of all you can see on p. 19 of my Origin of the Family, Private Property, and the State, the Punalua family is represented as developing so slowly that even in this century in the royal family there have been marriages between brothers and sisters. In antiquity we find examples of marriages between brothers and sisters, for instance, the Ptolemies. We must make a distinction between brothers and sisters on the mothers side and brothers and sisters on the fathers side. The Greek Adelphos (brother) and Adelphon (sister) are both derived from Delphos (mother), indicating thus the origin of brother and sister on the mother s side. And from the period of the Matriarchate there has been preserved for a long time the feeling that the children of one mother but of different fathers are more closely related than the children of one father but by different mothers. The Punalua form of the family excludes only marriages among the first, not among the second, since the latter, while the Matriarchate lasted, were not even considered relatives. Cases of matrimony between brothers and sisters in Ancient Greece are limited to those in which the contracting parties are descended from different mothers, or to those of whom the parental relationship was unknown, and hence the marriage was not forbidden. This, therefore, is not absolutely in contrast with the Punalua custom. You have noticed, then, that between the Punalua period and Greek monogamy there is a jump from the Matriarchate to the Patriarchate, which changes things considerably. According to the Greek Antiquities of Wachsmuth, one finds in the heroic period of Greece no trace of scruples due to a too close relationship of the contracting parties independently of the relationship between the parents and children. (P. 156.) Marriage with a carnal sister was not at all scandalous in Crete. (Ibid., p. 170.) This last affirmation is based on Strabone (X) but at the present moment I cannot find this passage because of faulty division of chapters. Under the expression carnal sister I understand, until proof to the contrary is furnished, a sister on the part of the father. I have interpreted your first main phrase in the following way: According to the Materialist Conception of History, the factor which is in the last instance decisive in history is the production and reproduction of actual life. More than this neither Marx nor myself ever claimed. If now someone has distorted the meaning in such a way that the economic factor is the only decisive one, this man has changed the above proposition into an abstract, absurd phrase which says nothing. The economic situation is the base, but the different parts of the structure-the political forms of the class struggle and its results, the constitutions established by the victorious class after the battle is won, forms of law and even the reflections of all these real struggles in the brains of the participants, political theories, juridical, philosophical, religious opinions, and their further development into dogmatic systems-all this exercises also its influence on the development of the historical struggles and in cases determines their form. It is under the mutual influence of all these factors that, rejecting the infinitesimal number of accidental occurrences (that is, things and happenings whose intimate sense is so far removed and of so little probability that we can consider them non-existent, and can ignore them), that the economical movement is ultimately carried out. Otherwise the application of the theory to any period of history would be easier than the solution of any simple equation. We ourselves make our history, but, primarily, under pre-suppositions and conditions which are very well determined. But even the political tradition, nay, even the tradition that man creates in his head, plays an important part even if not the decisive one. The Prussian State has itself been born and developed because of certain historical reasons, and, in the last instance, economic reasons. But it is very difficult to determine without pedantry that, among the many small States of northern Germany, precisely Brandenburg has been destined by economic necessity and not also by other factors (above all its complications with Poland after the Prussian conquest and hence, also, with international politics-which, besides has also been decisive in the formation of the power of the Austrian ruling family), to become that great power in which are personified the economic, linguistic, and-after the Reformation-also the religious difference between the North and South. It would be mighty difficult for one who does not want to make himself ridiculous to explain from the economic point of view the existence of each small German State of the past and present, or even the phonetic differentiation of High German which extended the geographic division formed already by the Sudetti mountains as far as the Faunus. In the second place history forms itself in such a way that the ultimate result springs always from the conflicts of many individual wills, each of which in its turn is produced by a quantity of special conditions of life; there are thus innumerable forces which cross each other, an infinite group of parallelograms of forces, from which is derived one resultant-the historical event -which in its turn again can be considered as the product of an active power, as a whole unconsciously and involuntarily, because that which each individual wishes is prevented by every other, and that which results from it is a thing which no one has wished. In this way history runs its course like a natural process, and has substantially the same laws of motion. But, because of the fact that the individual wills-each of which wishes that to which it is impelled by its own physical constitution or exterior circumstances, i.e., in the last analysis, all economic circumstances (either its own personal circumstances or the general conditions of society)-do not reach that which they seek but are fused in one general media in a common resultant, by this fact one cannot conclude that they are equal to zero. On the contrary, each contributes to produce the resultant, and is contained in it. I would further ask you to study the theory from its original sources and not from secondhand works; it is really much easier. One can say that Marx has written nothing in which some part of the theory is not found. An excellent example of its application in a specific way is the Eighteenth Brumaire of L. Bonaparte. Also in Capital (III) are many illustrations. And also permit me to recommend to you my writings, Herr E. Duehring s Umwalzung der Wissenchaft, and Feuerbach und der Ausgang der Klassischen deutschen Philosophie, in which I have given the most ample illustrations of Historical Materialism which to my knowledge exists. That the young people give to the economic factor more importance than belongs to it is in part the fault of Marx and myself. Facing our adversaries we had to lay especial stress on the essential principle denied by them, and, besides, we had not always the time, place, or occasion to assign to the other factors which participate in producing the reciprocal effect, the part which belongs to them. But scarcely has one come to the representation of a particular historical period, that is, to a practical application of the theory, when things changed their aspect, and such an error was no longer permissible. It happens too often that one believes he has perfectly understood a new theory, and is able to manage it without any aid, when he has scarcely learned the first principles, and not even those correctly. This reproof I cannot spare to some of our new Marxists; and in truth it has been written by the wearer of the marvellous robe himself. [That is, by Marx. Editor.] To the first question:-Yesterday (I am writing these words on the 22nd of Sept.) I also found in Schomann, Greek Antiquities, Berlin, 1855, Vol. I, p. 52, the following words, which confirm definitely the explanation given by me. It is noteworthy that in later Greece marriages between brothers and sisters of different mothers were not considered incest. I hope you will not be dismayed by the terrible parentheses which for the sake of brevity overflow from my pen. And I subscribe myself .
Marx-Engels Correspondence: Engels to J. Bloch 1890