"Capital is dead labor, which, vampire-like, lives only by sucking living labor, and lives the more, the more labor it sucks"

Karl Marx is asserting that capital, or the accumulated wealth and methods of production in society, is basically the result of past labor that has actually been preserved and invested, however does not actually do anything by itself. Rather, the only manner in which capital can continue to accumulate and preserve its power is by exploiting the living labor of employees who produce brand-new worth that can be extracted and contributed to the capital stock. This process is compared to a vampire that feeds off the blood of its victims, getting stronger the more it takes. In Marx's view, this dynamic ultimately causes the concentration of wealth and power in the hands of a little elite (the capitalist class) while the majority of individuals are left with little control over their own lives and work for a wage that hardly sustains them.