in me if I had confined myself to the actual wording of the original in the new edition in spite of the later and international form which it had assumed.
Where I wished to make changes had particular reference to two points. In the first place with regard to primitive history, as far as known, to which Morgan was the first to give us the key in 1877. In my book "The Origin of the Family, Private Property and the State," Zurich, 1884, I have since had an opportunity of working up material more lately accessible which I employed in this later work. In the second place, as far as that portion which is concerned with theoretical science is concerned, the presentation of the subject is very defective and a much more definite one could now be given. If I did not allow myself the right of improving it now, I should be in duty bound to pass criticism on myself instead of the other.
Marx and I were probably the first to import the well known dialectic of the German idealistic philosophy into the materialistic view of nature and history. But to a dialectical and at the same time materialistic view of nature there pertains an acquaintance with mathematics and natural science. Marx was a sound mathematician but the sciences we only knew in part, by fits and starts, sporadically. After I retired from mercantile pursuits and went to London and had time, I made as far as possible a complete mathematical and scientific "molting," as Liebig calls it, and spent the best part of eight years on it. I was occupied with this molting process when it chanced that I was called upon to busy myself with Herr Duehring's so-called philosophy. If, therefore, I often fail to find the correct technical expression, and am a little awkward in the field of natural science it is only too natural. On the other hand the
