pter in question was added to and it would
have been pedantic 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 consciousness of
insecurity which I have not yet got over has made me cautious. Actual
blunders respecting facts up to the present known, and incorrect
presentations of theories thus far recognised cannot be proved against
me. In this relation just one great mathematician, who is laboring
under a mistake, has complained to Marx in a letter that I have made a
mischievous attack upon the honor of the square root of minus one.

As regards my review of mathematics and the natural science it was
necessary for me to reassure myself on some special points--since I
had no doubts abo