A young student to impress his girl-friend: "I'm taking four courses at the unversity - German, French, Russian and Algebra!" His girl-friend:"Gee, you're a genius! Now, darling, do tell me I LOVE YOU in Algebra!"
In the fall of 1972 President Nixon announced that the rate of increase of inflation was decreasing. This was the first time a sitting president used the third derivative to advance his case for reelection. (From Hugo Rossi, Mathematics Is an Edifice, Not a Toolbox, Notices of the AMS, v. 43, no. 10, October 1996.)
A mathematician is a machine for turning coffee into theorems. (Attributed to both Alfréd Rényi and Paul Erdös.)
Die Mathematiker sind eine Art Franzosen; redet man mit ihnen, so übersetzen sie es in ihre Sprache, und dann ist es alsobald ganz etwas anderes. (Mathematicians are [like] a sort of Frenchmen; if you talk to them, they translate it into their own language, and then it is immediately something quite different.) Johann Wolfgang von Goethe.
Mathematics, rightly viewed, possesses not only truth, but supreme beauty -- a beauty cold and austere, like that of sculpture, without appeal to any part of our weaker nature, without the gorgeous trappings of painting or music, yet sublimely pure, and capable of a stern perfection such as only the greatest art can show. Bertrand Russell, The Study of Mathematics.
Every new body of discovery is mathematical in form, because there is no other guidance we can have. Charles Darwin.
A mathematician of the first rank, Laplace quickly revealed himself as only a mediocre administrator; from his first work we saw that we had been deceived. Laplace saw no question from its true point of view; he sought subtleties everywhere; had only doubtful ideas, and finally carried the spirit of the infinitely small into administration. Napoleon.
A topologist is one who doesn't know the difference between a doughnut and a coffee cup. John Kelley