Engels's letter to Marx of 24 August 1853 with remarks on Abraham Jacobi
F. Engels, a sprightly 33, lives in his father's house and is forever cadging money from him. He sneers at the intimate life of the 23-year-old A. Jacobi, who had spent a year in prison over the sham Cologne Communist Trial, been convicted of "insulting the majesty" of the King of Prussia, and at 21 had defended a doctoral dissertation in medicine at the University of Bonn.
This embittered gossip does not merely poke his nose into another man's bed: he also prophesies an unlucky professional fate for the young Abraham Jacobi.
It is worth noting that, firstly, by the time he met Engels Jacobi had already been a widower for two years; and secondly, in 1853 he emigrated to England, whence he moved on to the USA, where he took part in the Civil War, built a career, became a professor and even president of several medical societies, had a park and a medical centre in New York named after him, and, incidentally, outlived Engels by 24 years and had three children, whereas the childless father of communism brought up Marx's illegitimate son, born to a servant girl.