“Not Copernicus and Galilei [sic], when they abolished the Ptolemaic system; not Newton, when he annihilated the Cartesian vortices; not Young and Fresnel, when they exploded the ‘corpuscular theory’; not Faraday and Clerk-Maxwell, in their splendid victory over Actio in distans – more thoroughly shattered a malignant and dangerous heresy, than did Joule when he overthrew the baleful giant force, and firmly established, by lawful means, the beneficent rule of the rightful monarch, energy! Then, and not till then, were the marvelous achievements of Sadi Carnot rendered fully available; and Science silently underwent a revolution [see: thermodynamic revolution] more swift and more tremendous than ever befell a nation. But this must be a theme for the Poet of the Future!”

— Anon (1884), review of Joule’s Scientific papers [1]

“With the death of Lord Kelvin, on December 17 [1907], there passes away the grandest figure of contemporary science, and with it closes an epoch in the history of physics. When William Thomson was born, in 1824, Ohm's law of the flow of electric currents had not been discovered, Oersted's discovery of the magnetic action of the current was but four years old, while Faraday's capital discovery of the induction of currents was not to come for seven years. The wave theory of light had been but recently set on its feet by Young and Fresnel, and was not yet thoroughly believed, while the two laws of thermodynamics, perhaps the most important contribution of the nineteenth century, were unknown. All these things Lord Kelvin saw, and a great part of them he was. Probably no one, with the single exception of Helmholtz, born three years earlier, exercised greater influence on the science of the nineteenth century, while to compare the influence of these two great physicists with that of Darwin is as bootless as to question whether the grass is greener than the sky is blue.”

— Arthur G. Webster (1908), “Lord Kelvin”, Dec 22 [2]

“In choosing a theory, one should pay attention to simplicity in hypotheses only. Simplicity in computation can be of no weight in the balance of probabilities. Nature is not embarrassed by difficulties of analysis. She avoids complication only in means. Nature seems to be proposed to do much with little: it is a principle that the development of physics constantly supports by new evidence.”

— Augustin Fresnel (c.1820) (Ѻ)