Leonhard Euler

“ It is as though Nature wishes to achieve some effect, and approaches it as closely as possible. Not only is the truth of this principle evidence, but also the reasoning upon which it is based, and to destroy entirely the objections of Mr. König who, far from striking a blow against this principle, has wonderfully helped to confirm it. It is a specious criticism of the principle of least action to note that there are certain cases in which the action disappears entirely, since the action can assuredly not become smaller than zero. ”

“ Although the entire letter could not be rejected, it seemed plausible that certain phrases and even entire sentences had been introduced, and that one did not make them match sufficiently with the remaining text. On top of this suspicion, it seemed regrettable that the credibility of this fragment depended entirely on the testimony of a man who had lost his head; and that such testimoney was insufficient to establish its authenticity. ”