Let ε < 0.

For people with small horizons, every function is constant. (Oscar Bruno)

All you need for differentiation is a strong right arm and a weak mind. (Ron Getoor)

Obvious is in the the of the beholder. (Ron Getoor)

Sometimes the Devil lurks in sets of measure zero. (Ron Getoor)

There are two kinds of results in mathematics: those that are obvious and those that are false. (Ron Getoor)

There are no deep theorems — only theorems that we have not understood very well. (Nicholas P. Goodman)

The world is everywhere dense with idiots. (L. F. S.)

It’s only the false things that are nontrivial. (Michael Sharpe)

Everything is trivial when you know the proof. (D. V. Widder)

My thanks to Jason Lee, who compiled many of these.

The good Christian should be aware of mathematicians and all those who make empty prophecies. The danger already exists that mathematicians have made a covenant with the devil to darken the spirit and confine man in the bonds of Hell. (St. Augustine) ¹

A man whose mind has gone astray should study mathematics. (Francis Bacon)

A person who can, within a year, solve x² – 92y² = 1 is a mathematician. (Brahmagupta)

A mathematician is a blind man in a dark room looking for a black cat which isn’t there. (Charles R Darwin)

A mathematician is a device for turning coffee into theorems. (P. Erdos)

Mathematicians, like cows in the dark, all look alike to me. (Abraham Flexner)

Mathematicians are like Frenchmen: whatever you say to them, they translate it into their own language, and forthwith it means something entirely different. (Johann Wolfgang von Goethe)

Medicine makes people ill, mathematics make them sad and theology makes them sinful. (Martin Luther)

He who can properly define and divide is to be considered a god. (Plato)

God geometrizes. (Pluto)

Tai Melcher suggested including this quote. Quoth she, “Maybe if they’re scared of us, they won’t laugh at us anymore. Or at least not as loudly.”

The four branches of arithmetic — ambition, distraction, uglification and derision. (Lewis Caroll, Alice in Wonderland)

As far as the laws of mathematics refer to reality, they are not certain, and as far as they are certain, they do not refer to reality. (Albert Einstein)

If you can’t explain what you are doing to a nine-year-old, then either you still don’t understand it very well, or it’s not all that worthwile in the first place. (Albert Einstein)

Only two things are infinite: the universe and human stupidity, and I’m not sure about the former. (Albert Einstein)

The two most common things in the Universe are hydrogen and stupidty. (Harlan Ellison)

I’ve heard that the government wants to put a tax on the mathematically ignorant. Funny, I thought that’s what the lottery was! (Gallagher)

Old mathematicians never die; they just lose some of their functions. (John C. George)

I turn away with fear and horror from this lamentable plague of functions which do not have derivatives. (Hermite, in a letter to Stieltjes)

Mathematics is a game played according to certain simple rules with meaningless marks on paper. (David Hilbert)

Physics is much too hard for physicists. (David Hilbert)

A Ph.D. dissertation is a paper of the professor written under aggravating circumstances. (Adolf Hurwitz)

Nature laughs at the difficulties of integration. (Pierre-Simon de Laplace)

Everything good is either illegal, immoral, or equivalent to the Axiom of Choice. (Josh Laison)

If I have seen farther than others, it is because I was standing on the shoulder of giants. (Isaac Newton)

If I have not seen as far as others, it is because giants were standing on my shoulders. (Hal Abelson)

Mathematicians stand on each other’s shoulders. (Gauss)

Computer scientists stand on each other’s feet. (Richard Hamming)

Software engineers dig each other’s graves. (unknown)

Mathematics is like checkers in being suitable for the young, not too difficult, amusing, and without peril to the state. (Plato)

Mathematics consists of proving the most obvious thing in the least obvious way. (George Polya)

As long as algebra is taught in school, there will be prayer in school. (Cokie Roberts)

Algebraic symbols are used when you do not know what you are talking about. (Philippe Shnoebelen)

Basic research is what I am doing when I don’t known what I am doing. (Werner von Braun)

In mathematics you don’t understand things. You just get used to them. (Johann von Neumann)

Five out of four people have trouble with fractions. (Steven Wright)