This lecture from Yale instructor Paul North's chapter by chapter study of Marx's Capital, Volume 1, arrives at what North describes as the center of the book, introducing the core mechanics of Marx's argument. The session defines relative surplus value, the surplus generated by increasing productivity rather than extending working hours, distinguishing it from the absolute surplus value covered in earlier chapters. North treats this section as pivotal to understanding Capital's broader argument about how capitalist production continually reorganizes labor. The lecture sets up the following classes on the division of labor and machinery, continuing the course's close, sequential reading of the 1872 text.