This is a synopsis of Capital, Volume I, written by Engels in 1868. Upon Capital's release, Engels began constructing a comprehensive summation
On April 17, 1868, he wrote Marx: "I have a limited time at my disposal and the summarising of your book requires more work than I thought; after all, once having taken up the work, I must do it properly...." Engels' synopsis serves two useful contributions: First, Engels was a far more rapid writer than Marx, and more readable. Second, Engels could distance himself from the massive web of ideas without "losing his place in it", and identify primary points to be made.
Engels could achieve this because he was intimately involved with the production of Capital. Marx forwarded sheets to Engels as they were printed; Engels sent back his impressions and thoughts.
This text was published in Fortnightly Review. Engels only summarized the first four chapters of Volume I of Capital.
NOTE: In the first edition, Volume I was divided into six chapters. Subsequent editions renamed these chapters "parts". The 5th chapter was broken into two parts; so that a total of seven parts resulted. The four chapters summarized by Engels therefore correspond to the first four parts of Capital as found today. Also note Marx made additions and alterations to the text in subsequent editions. For example, Marx did not dwell in the 1st chapter/part (Commodities) on value and exchange-value -- so Engels' synopsis doesn't deal with that subject, which is today integral to chapter one.
In the Progress Publishers introduction, we find:
The reviews and the synopsis made by Engels are inestimable aids to the study of Capital. The contents of Capital are given for the greater part in Marx's own words.
The centre of gravity, in the synopsis, as well as in the reviews, lies in the theory of surplus-value, the corner-stone of Marx's economic doctrine. Engels summarized Marx's theory of surplus-value with special care, characterizing in detail the historical circumstances in which the relations of capital exploitation spread, the working class made its first steps in the struggle and the first skirmishes took place between labor and capital.
Engels' synopsis that the transition from one category to another is not a freak of reason but the reflection of the real historic process of development. Keeping to the order of Marx's exposition, he shows how, in the course of historic development, capital emerged on the basis of commodity production, how it subordinated to itself the whole of production, how simple co-operation was replaced by manufacture and this, in turn, by machine production.