The most famous expounders of logic are reproached for their cumbrous style and their obscure mode of explanation. Even masters of languages have complained in my hearing about the foreign terms used by that branch of science, terms which even they could not understand. Much of the blame for this condition of things may fall on the difficulties of the subject, which have baffled all elucidation for thousands of years. Some of the blame also falls on the bad habit of using learned vernacular. But the greatest fault lies with the mental laziness of the students. Nothing can be learned without mental exertion. If you are concerned in your further development, you will recognize the Christian word as to the curse of work as untrue. Work cannot be descended from sin, for it is a blessing. You will have experienced in yourself how elated one feels after successful physical or mental work. The things which science yields without exertion can be at most axiomatic commonplaces. I assume that you are quite willing to perform the necessary mental labor, and I promise you that I shall do my best to make this study easy for you. I do this so much more readily, as I frankly confess that these letters to my son are written with the intention of making them accessible to a wider circle of readers by means of the press. Before concluding, let me say a word about my aim of speaking especially of democratic-proletarian logic. You will think or say: Logic may be a subject worthy of study, but a special democratic-proletarian logic can surely treat of nothing but party matters. But just as the special accomplishments in this or that line, the special advances of this or that nation, are at the same time general advances, progress of civilization, so the ideas of proletarian logic are not party ideas, but conclusions of logic in general. You may reply: Even though the special thought of a Chinaman may be quite consistent and logical, still we would not call it Chinese logic. That would be quite true, but it does not meet my point. The thought on which the proletarian demands are based, the idea of the equality of all human beings, this ultimate proletarian idea, if I may say so, is fully backed up by the deeper insight into the tortuous problem of logic. Now, since this idea dominates mankind, it certainly has more right than any Chinese idea. Furthermore, industrial development has leveled, simplified, cleared all social conditions to such an extent that it becomes ever easier to penetrate with sober eyes into the secrets of logic. Finally, my logic deserves its proletarian qualification for the reason that it requires for its understanding the overcoming of all prejudices by which the capitalist world is held together. The cause of the people is not a party matter, but the general object of all science.