In psychology, reserve energy is a theory which supposes that in people there are reservoirs of surplus energy, both mental and physical in variety, that when successfully tapped present resistances to fatigue. [1]

In 1890s, American psychologist William James (1842-1910), while theorizing about energy and mental ability, was hiking in the Adirondack Mountains, and during this time was told by one of his guides about how hikers, in many cases, may feel cold when they start the hike, but as they progress into will warm up to the climb, getting second wind or even a third or fourth wind; the gist of which he states in his own words as follows:

“Everyone knows what it is to start a piece of work, either intellectual or muscular, feeling stale—or ‘cold’, as an Adirondack guide once put it to me. And everybody knows what it is to ‘warm’ up to the job. The process of warming up gets particularly striking in the phenomena known as second wind. On usual occasion we make a practice of stopping an occupation as soon as we meet the first effective layer (or so to call it) of fatigue. We have then walked, played, or worked enough, we desist. That amount of fatigue is an efficacious obstruction on this side of which our usually life is cast.”

“But if an unusual necessity forces us to press onward, a surprising thing occurs. The fatigue gets worse up to a certain critical point, when gradually it passes away, and we are fresher than before. We have evidently tapped a level of new energy, masked until then by the fatigue obstacle usually obeyed. There may be layer after layer of this experience. A third and forth wind may supervene. Mental activity shows the phenomenon as well as physical, and in exceptional cases we may find, beyond the very extremity of fatigue distress, amounts of ease and power that we never dreamed ourselves to own—sources of strength habitually not taxed at all, because habitually we never push though the obstruction, never pass those early critical points.”

Sometime thereafter, James began to discuss and or teach this new "reserve energy" theory of mental ability to his student Boris Sidis, who had recently emigrated to the US in 1887 to escape political persecution.

In 1898, Boris' son William Sidis was born, and with him began to test out, in theory, James' reserve energy theory on the new child, the result of which became the most-famous of all forced prodigy experiments. [3]

The younger Sidis, in 1920, published his The Animate and the Inanimate, arguing that the existence of “reserve energy” in life forms represents a reversal of the second law of thermodynamics. [4]

In 1907, William James, in his “The Energies of Men”, stated an outline of his reserve energy theory. [2] James, supposedly, claimed to have discovered this hidden energy principle concurrently with his protege Russian-born American psychologist Boris Sidis. [6]

Boris Sidis, in the experimental accelerated education of his now-famous son, child protege William Sidis, who, by his father's accelerated home education and teachings, was qualified to enter Harvard at age nine, graduating at age 16, resulting to have an adulthood IQ of 250-300. These combination of theory and successful application became the basis to the now-famous "10 percent myth" as popularized by American author Lowell Thomas in the introduction to the decade-long 1936 best-seller New How to Win Friends and Influence People.

In the 1910s, this reserve energy principle was beginning to be termed the “law of reserve energy”. [3] This law was argued to represent a capacity for withstanding pains, aches, and conquering disinclinations that would otherwise seem impossible. The summarizing statement of the law of reserve energy is: [4]

“Organisms have stored reserves of energy that are ordinarily not called upon, but that may be called upon … and be ready for use for anyone who probes so deep.”

In 1986, American biographer Amy Wallace commented that according to one 1910 restatement of what was termed Boris' theory of reserve energy (or the doctrine of reserve energy) "each of us possess a stored-up fund of energy, of which we ordinarily do not make any use, but which we could be trained to use habitually to our great advantage. Dr. Sidis contends that it is by arousing this potential energy that the patients whom he treats are cured; he further insists that, by the remarkable results he has obtained in educating his boy, he has demonstrated the possibility of training people to draw readily and helpfully on their hidden energies.” [5]

1. Walsh, James J. (1912). Psychotherapy, (pg. 92). D. Appleton.
2. (a) James, William. (1907). “The Energies of Men” (GoogleBooks), (JSTOR), [URL], (Wikisource), Science 1, Vol. 25, no. 635. pgs. 321-32. March.
(b) Speech: “The Energies of Men” delivered as the Presidential Address before the American Philosophical Association at Columbia University, Dec. 28, 1906.
3. Abbott, Lyman, Mabie, Hamilton W., Abbott, Ernest H., Bellamy, Francis R. (1914). The Outlook (pg. 148). Outlook Co.
4. Sidis, William J. (1920). The Animate and the Inanimate, [PDF], (published in 1925, R.G. Badger).
5. Bruce, H. Addington. (1910). “Bending the Twig” (discusses Boris’s reserve energy theory), American Magazine, Vol. 69: 690-95, Mar.
6. Wallace, Amy. (1986). The Prodigy: a Biography of William James Sidis: America's Greatest Child Prodigy (reserve energy, pgs. 31-32, 52-53, 57, 158-59). Dutton Adult.

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