The take-off of the First Industrial Revolution in England around the mid-eighteenth century, which shifted manufacturing to the factory system, was due to the emergence of the new entrepreneurial class with highly skilled and culturally informed technicians who fully assimilated the values of capitalism and transferred them to their fundamental innovations. One could apply the Gramscian concept of “hegemony” to describe the spread of new literary and philosophical societies in which entrepreneurs, technicians, and intellectuals met to discuss solutions to newly emerging problems. Inventions that increased labor productivity flourished, and in the field of energy production, where water wheels and steam engines already existed, decisive advances were to streamline their use in capitalist production, which prevented future developments because science was still tied to old approaches. The contributions of John Smeaton to the development of water wheels, and of James Watt to the steam engine are analyzed here in detail, emphasizing how both led to the completion of Newtonian mechanics and the birth of thermodynamic science. The concept of efficiency that inspired their research was destined to inform all of modernity. In those same years in France, the regime of absolutism prevented the nascent bourgeoise from establishing their hegemony. Through the Enlightenment movement, they sublimated their planning by studying and systematizing the achievements of British “practical mechanics” in a rational sense. In particular, Lazare Carnot, trained in the school of military genius, generalized the criteria that Smeaton had established for water wheels to all mechanical machines, introducing the first formalizations of energy concepts. Lazare’s son, Sadi Carnot, inspired by the same criteria, formulated the first theory of “fire machines” in 1824, opening up the modern field of thermodynamics, which introjected from its inception the criterion of efficiency.