[M]achines too "work" or produce value, . . . they have always worked, and . . . they work more and more in proportion to man, who thus ceases to be a constituent part of the production process, in order to become adjacent to this process. [AO: 232]
Hence there is a machinic suplus value produced by constant capital, which develops along with automation and productivity, and which cannot be explained by factors that counteract the falling tendency--the increasing intensity of the exploitation of human labour, the diminution of the price of the elements of constant capital, etc.--since, on the contrary, these factors depend on it. [AO: 232]