This book, entitled Correspondence between Friedrich Engels and Karl Marx 1844-1883, Volume One, is a collection of letters between two prominent figures of socialist ideas, Friedrich Engels and Karl Marx. The correspondence begins in 1844 and continues until 1883, covering a rich period in their friendship and collaboration. In this book, the reader will be able to learn more about the ideas of these great philosophers, their attitude to society, politics and culture of that time. The letters reveal the personal reflections of the authors, their mutual advice and discussion of theoretical issues that became the basis of social theory. This first volume is an important source for those interested in the development of socialist thought and who want to better understand the interaction between the two key figures of the nineteenth century. The book allows you to better understand the history and context surrounding these outstanding figures and understand the significance of their contribution to the development of socialist ideas.