Einstein (writing by window)
German-born American physicist Albert Einstein (1879-1955), eponym of the Einstein postulate (c.1940) in his personal library.
In science, the Einstein postulate is the following statement:

Thermodynamics is only physical theory of universal content which I am convinced will never be overthrown, within the framework of applicability of its basic concepts.”

This conclusion was famously surmised in the 1940s by German-born American physicist Albert Einstein, who in retrospect reasoned that among the various sciences, the science of thermodynamics is the one subject least likely in all of science to ever be overthrown. The exact statement made by Einstein is as follows: [1]

"A theory is the more impressive the greater the simplicity of its premises, the more different kinds of things it relates, and the more extended its area of applicability. Therefore the deep impression that classical thermodynamics made upon me. It is the only physical theory of universal content which I am convinced will never be overthrown, within the framework of applicability of its basic concepts."

This is one of the most-famous quotes in thermodynamics and situates thermodynamics as the hardest of all sciences.

A version of the so-called Einstein postulate was stated in 1903 by American Henry Adams who in his research to see how modern physical science would apply to the humanities, particularly in the study of history, commented in a letter to a friend that: [2]

“Mathematicians and physicists are almost epileptic in their convulsive assurances that the laws of thermodynamics have reached a generalization which will hold good.”

In other words, by start of the 20th century, the first and second laws of thermodynamics had reached a point nearly uniform acceptance.

See also
Clausius postulate
Eddington rule

References
1. (a) Schlipp, P.A. (1973). Albert Einstein: Philosopher-Scientist. La Salle, IL.: Open Court Publishing.
(b) Einstein, Albert. (author), Paul Arthur, Schilpp (editor). (1979). Autobiographical Notes. A Centennial Edition, (p. 31). Open Court Publishing Company.
(c) As quoted by Don Howard, John Stachel. Einstein: The Formative Years, 1879-1909 (Einstein Studies, vol. 8). Birkhäuser Boston. 2000. (p. 1).
2. Adams, Henry, Samuels, Ernest. (1992). Henry Adams, Selected Letters (thermodynamics, pgs. 438 (quote), 466, 517). Harvard University Press.

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