Mathematicians Of The Day

15th June

On this day in 1641, in a letter to Bernard Frenicle de Bessy, Fermat called the theorem that every prime of the form 4n + 1 is the sum of two squares, the fundamental theorem of right triangles.  He stated that he had a proof that was "irrefutable".  Later he suggested he had a proof by infinite descent.  Euler is credited with the first correct proof of the theorem, still called Fermat's theorem.

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Quotation of the day

From Bernard Lamy
A discourse is beautiful when it is composed according to the Rules of Art; it is great when it is more than ordinary perspicuous; when there is not one equivocation; no sentence unintelligible; no expression ambiguous; when it is well-disposed, and the mind of the Reader led directly to the end of the design, without the remora or impediment of impertinent words. Such clearness like a Torch dispels all obscurity and makes every thing visible.
De l'Art de parler (1675)