necessities of nature, it is, therefore,
necessarily a product of historical development. The first human
beings to become differentiated from the lower animals were in all
essentials as devoid of freedom as these animals themselves but each
step in human development was a step towards freedom. At the threshold
of human history stands the discovery of the transformation of
mechanical motion in heat, the generation of fire by friction; at the
close of development up to the present stands the discovery of the
transformation of heat into mechanical motion, the steam engine. In
spite of the tremendous revolution in the direction of freedom which
the steam engine has produced in society it is not yet half complete.
There is no question that the production of fire by friction still
surpasses it as an agent in the liberation of humanity. Because the
production of fire by friction for the first time gave man power over
the forces of nature and separated him for ever from the lower
animals. The steam engine can never bridge so wide a chasm. It appears
however as the representative of all those productive forces by the
help of which alone a state of society is rendered possible in which
no class subjection or pain will be produced by reason of the lack of
means for the sustenance of the individual, in which moreover it will
be possible to speak of real human freedom as arising from living in
accordance with the recognised laws of nature. But considering the
youth of humanity it would be absurd to wish to impute any universal
absolute validity to our present philosophical views, and it follows
from the mere facts that the whole of history up to the present time
is to be regarded as the history of the period extending from the time
of the practical discovery of the transformation of mechanical
movement into heat to that of the transformation of heat into
mechanical movement.

(The above constitutes a reply to the view which regards history
simply as the record of human error and is followed by a discussion of
Duehring's opinions in that regard.)

CHAPTER VII

THE DIALECTIC

_Quantity and Quality._

(Here Herr Duehring contends "The first and most important statement
with respect to the foundation logical properties of existence points
to the exclusion of contradiction. Contradiction is a category which
can belong to thought alone but which can pertain to nothing real.
There are no contradictions in things; in other