By publishing in a separate brochure the complete collection of letters from Marx to Kugelmann, which were published in the German social-democratic weekly review Neue Zeit, we have made it our duty to introduce the Russian public more closely to Marx and Marxism.

As one would naturally expect, a very large part of Marx's correspondence is dedicated to personal matters. For the biographer, all of this constitutes extremely valuable material. For the broad public in general, and for the working class of Russia in particular, those points in the letters that contain theoretical and political material are incomparably more interesting.

Especially for us, in the revolutionary era we are living in, it is very instructive to delve into this material, in which we see Marx directly addressing all the problems of the labor movement and global politics.

The editorial staff of Neue Zeit is absolutely right to observe that "we are elevated by our acquaintance with the forms of the people whose thoughts and wills were shaped under the conditions of great upheavals." (Excerpt from the preface by V.I. Lenin to the Russian translation of the work in 1907).