"The proletarian who sells his labouring power to the capitalist is paid a wage which corresponds only to a part of the time of labour he spends, the value of the rest, the surplus value, being pocketed by the employer. This viewpoint eloquently proves that all the wealth of the bourgeoisie is made up of the surplus value produced by the proletariat and appropriated by the capitalists."
January 1, 1970
https://en.wikiquote.org/wiki/Tr%C6%B0%E1%BB%9Dng_Chinh