I propose this theorem to be proved or problem to be solved. If they succeed in discovering the proof or solution, they will acknowledge that questions of this kind are not inferior to the more celebrated ones from geometry either for depth or difficulty or method of proof

— Pierre de Fermat, Letter to Frénicle (1657)

Source: http://books.google.com/books?id=L6QKAAAAYAAJ

Quoted by Edward Everett Whitford in The Pell Equation (1912).

Topics: mathematics