He's talking about the manifesto, which was written so thay your average literate person could understand in the 19th century. Marx himself suggested that you don't start Capital from chapter one because its the most philosophical and complicated part of the book. He suggested people look at chapter three or something I can find my copy of capital with an intro from the 1890s where he said kinda sexistly that women shouldn't start with the first chapter because of how heavily it leans on Hegelian philosophy.

I wish he had lived long enough to write his book on the state 🙁