this development has arrived at a point where the mass becomes conscious of itself. Man has hitherto developed by class antagonism. By this means he has now arrived at the point where he wants to develop himself consciously. Class antagonisms were _phenomena_ of humanity. The working class strives to abolish class antagonism in order that humanity itself may be a _truth_. Just as the Reformation was conditioned on the actual environment of the sixteenth century, so, like the discovery of the electric telegraph, the research of the theory of human understanding is based on the actual conditions of the nineteenth century. To this extent the contents of this little work are not an individual, but a historical product. In writing it, I feel myself, if I may use this mystic phrase, as a mere organ of the idea. Only the form of presenting the subject is mine, and I beg the kind reader to judge it leniently. I ask that the reader may direct his or her silent or loud objections, not against the form, but against the substance of my remarks, not to cling to the letter, but to understand the spirit of my words. If I should not succeed in developing the idea, and if my voice should thus be drowned in the hubbub of our overstocked book market, I am nevertheless certain that the cause itself will find a more talented champion. JOSEPH DIETZGEN, _Tanner_. SIEGBURG, May 15, 1869. THE NATURE OF HUMAN BRAIN WORK I. INTRODUCTION Systematization is the essence and the general expression of the aggregate activity of science. Science seeks to classify and systematize the objects of the world for the understanding of our brain. The scientific understanding of a certain language, e. g., requires an orderly arrangement of that language in general categories and rules. The science of agriculture does not simply wish to produce a good crop of potatoes, but to find a system for the methods of cultivation and thus to furnish the knowledge by which success in cultivation can be determined beforehand. The practical result of all theory is to acquaint us with the system and method of its practice and thus to enable us to act in this world with a reasonable certainty of success. Experience is, of course, an indispensable condition for this purpose; but it alone is not sufficient. Only by means of empirically developed theories, by science, do we overcome the play of accident. Science gives us the conscious domination over things and unconditional security in handling them. No one individual can know everything. The capacity of the individual brain is no more adequate for the knowledge of everything that is necessary than the skill and strength of the individual's hands are sufficient to produce all he needs. Faith is indispensable to man, but only faith in that which others know, not in what they believe. Science is as much a social matter as material production. "One for all and all for one."