Written more than 150 years ago, reproduces a series of lectures given to workers, in which Marx presented in popular form some fundamental concepts on how wages are defined, on the nature of capital, on the value and price of commodities, and on relations between capital and wage labor in modern bourgeois society. As Engels recalls in his Introduction, the theses supported by Marx in this short book were further developed in his main work, , which contains his most in-depth analysis of the capitalist production system. , however, has also stood the test of time and still presents itself as a model of popular exposition in which the clarity and simplicity of the language are combined with scientific rigor. The modern reader will be able to discover here, in just a few pages, the foundations of Marx's thought and the proletariat's struggle against the slavery of capital.