
An artistic rendition of a water mill, according to which the power of the fall of water through a height, i.e. work per unit time or water power, "drives" the mechanical operation of the mill, which is to grind grain.

An artistic rendition of a water mill, according to which the power of the fall of water through a height, i.e. work per unit time or water power, "drives" the mechanical operation of the mill, which is to grind grain.

In industry, waterpower or water-power is defined as the power of water employed to move machinery or the fall of water suitable for being used to move machinery. [1] This was the primary means of powering the operation of factories, prior to the industrial revolution, initiated in 1702 by the functional development of English engineer Thomas Savery’s engine. [2]

In this sense, a proximity to bodies of water was a necessary prerequisite to the development of mills and later towns around mills. To exemplify, in his Pirotechnica of 1540, Italian metallurgist Vannoccio Biringuccio stated that:

“Of all the inconveniences, shortage of water is the most to be avoided, for it is a material of the utmost importance in such work, because wheels and other ingenious machines are driven by its power and weight.”

Typically, to obtain power from water, an amount of water from a river, impoundment, or mill pond is diverted to a turbine or water wheel, along a channel or pipe. The force of the water's movement drives the blades of a wheel or turbine, which in turn rotates an axle that drives the mill's other machinery.

Thermodynamics
In 1823, French engineer Sadi Carnot, in his Reflections on the Motive Power of Fire, famously stated that the “fall of caloric”, from the hot body (boiler) to the cold body (condenser), through the working substance in the operation of the steam engine, is comparable, in principle, to the “fall of water”, from the higher location, through the rotary mechanism of the water mill, to the lower location, in the machines operated by falling water, in the production of motive power.

Drive theory
In 1930, Austrian psychologist Sigmund Freud stated, in his Civilization and its Discontents, that the starting point for his famous 1895 conceived free energy and bound energy connected 1910 "drive theory" basis for his libido energy (id, ego, superego) model of the "theory of instincts" of psychoanalysis from the final line of Friedrich Schiller's 1795 "The World Way" poem, which according to the 1961 translation by James Strachey, Freud quotes as follows:

“Hunger and love are what moves the world.”
— Friedrich Schiller (1795), quoted by Sigmund Freud, in Civilization and its Discontents (1930) (Ѻ), as basis if his drive theory (Ѻ)

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See also
● Horsepower
● Manpower
● Social power

References
1. Manpower – Merriam-Webster Collegiate Dictionary, 2000.
2. Kirby, Richard S., Withington, Sidney, Darling, Arthur B., and Kilgour, Frederick, G. (1956). Engineering in History, (pgs. 154, 171-72). New York: McGraw-Hill.
3. Biringuccio, Vannoccio. (1540). Pirotechnia of Vannoccio Biringuccio (American Institute of Mining and Metallurgical Engineers, New York, 1942, pg. 22).