In textbook economics, the economic weight of a factor of production (its output elasticity) is equal to its share in total factor costs. According to this cost share theorem, the factors of production would have approximately the following weights: human labour 70%, (real) capital 25% and energy only 5%, provided that it is recognised as a genuine factor of production at all. With this factor weighting, however, the economic slumps and recoveries in the wake of the oil price shocks of the 1970s and early 1980s as well as the first global economic crisis of the twenty-first century cannot be understood. In addition, the growth of value added calculated for industrialized countries is deeply below that observed empirically. Orthodox economics attributes the large difference to something whose physical components are not known and which is called “technical progress”. If one calculates the equilibrium state in which an economy presupposedly operates according to the optimization of profit or welfare, taking into account the technological constraints to which the combinations of capital, labor, and energy are subject, one finds that the cost-share theorem is a special case that is invalidated through the historical path of factor quantities and prices. An alternative method of calculating output elasticities developed for the current, real economies is based on the law of diminishing returns and the mapping of the trend towards increasing automation in the course of digitalisation. This yields good agreement between empirically observed and theoretically calculated economic growth for the Federal Republic of Germany and the USA between 1960 and 2013, and one finds that the economic weight of human labor is much smaller and that of energy much larger than the respective cost share of these two production factors. Thus, it is also shown econometrically to what extent the industrialized countries owe their material prosperity to energy, which activates the capital stock.