In his ground-breaking work, “The Condition of the Working Class in England”, Engels argued that the history of the proletariat was bound up with the invention of the steam-engine and "machinery for working cotton" in the second half of the 17th century. These instruments gave rise to the industrial revolution which produced new instruments of labor, new industries, a new social structure, and new living and working conditions. Engels says that in his age that the greatest advance in human control of nature, and thus in freedom, was the invention of the STEAM ENGINE and the modern world that it has made possible. Engels thought that the steam engine had so increased the productive forces of humankind that we could, in the age of steam, solve social inequalities. For the development of the productive forces "make possible a state of society in which there are no longer class distinctions" in which there be will enough socially created product for all and "for the first time there can be talk of real human freedom"-- that is, "of an existence in harmony with the laws of nature that have become known."