The collected works reflect the whole complex of ideas included in the worldviews of the founders of scientific socialism Marx and Engels. It provides an objective basis for the scientific study of all issues related to their lives and activities. Here are given not only works in the literal close sense of the word, not only all already printed articles, but also all unpublished works remaining in the manuscript, all unpublished articles and excerpts. All letters of philosophers are given, all letters to them that have any significance for the coverage of their personalities, especially their practical political activities.