### Favorite funny stories about mathematicians

Below I have collected some of my favorite quotations. I also provide the original references of them.

In 1817, when lecturing before private society in London on the element chlorine, Faraday thus expressed himself with reference to this question of utility. “Before leaving this subject, I will point out the history of this substance as an answer to those who are in the habit of saying to every new fact, ‘What is its use?’ Dr. Franklin says to such, ‘What is the use of an infant?’ The answer of the experimentalist is ‘Endeavour to make it useful’ When Scheel discovered this substance, it appered to have no use; it was in its infancy and useless state, but having grown up to maturity, witness its powers and see what endeavours to make it useful have done.”

[Henry Bence Jones (1813–1873) angol
kémikus 1870-ben megjelent *The Life and Letters of Faraday* könyvének első kötetében a 218. oldalon, valamint
John Tyndall (1820–1893) ír fizikus 1868-ban megjelent Faraday as a Discoverer
című könyvének 35. oldalán. Érdemes még
elolvasni ezt a cikket is, amely részletesen tárgyalja ennek és a következő anekdotának az eredetét.]

The Prime Minister is said to have asked Faraday what use of his discovery of electromagnetism might have. “Soon you will be able to tax it.”

[See page xxxi of the book Democracy and Liberty written by William Edward Hartpole Lecky (1838–1903).]

In Cambridge, they tell the following story about Maxwell: Maxwell was lecturing and, seeing a student dozing off, awakened him, asking, “Young man, what is electricity?” “I'm terribly sorry, sir,” the student replied, “I knew the answer but I have forgotten it.” Maxwell’s response to the class was, “Gentlemen, you have just witnessed the greatest tragedy in the history of science. The one person who knew what electricity is has forgotten it.”

[See pages 55– of the nice book Random Walks and Electric Networks written by Peter G. Doyle and J. Laurie Snell.]

Once when lecturing in class Lord Kelvin used the word
“mathematician” and then interrupting himself asked his class: “Do you know
what a mathematician is?” Stepping to his blackboard he wrote upon it:
integral from minus infinity to plus infinity of exp(-x^2)dx = sqrt(pi). Then
putting his finger on what he had written, he turned to his class and said,
“a mathematician is one to whom *that* is as obvious as that twice two
makes four is to you. Liouville was a mathematician” Then he resumed his lecture.

[See Volume 2, page 1139 of the book the book The Life of William Thomson Baron Kelvin of Largs written by Silvanus Phillips Thomson (1851–1916).]

In 1916, Hugo Steinhaus, who had been staying in Kraków for some time, was taking an evening walk in the Planty Gardens, when he unexpectedly heard someone utter the words “Lebesgue integral.” It turned out that two young men,Stefan Banach and Otto Nikodym, were sitting on a bench and talking about modern mathematics. Steinhaus joined the conversation. Banach and Nikodym told him that they often discussed mathematics and that they were frequently joined in their debates by a third friend, Witold Wilkosz. In the ensuing conversation, Steinhaus told them about a problem he had been working on, and after a few days Banach brought him a solution. This result was published 2 years later in a joint paper by Banach and Steinhaus in the Bulletin of the Academy of Arts and Sciences in Kraków; it was Banach’s first research paper. Steinhaus would often say later that his greatest mathematical discovery was Banach.

[See Banach in Kraków: A Case Reopened.]

There is a story that emanates from the high table at Trinity that is instructive in this regard. G. H. Hardy, the pure mathematician—to whom I owe all that I know of pure mathematics—remarked on this remarkable fact, and some-one took him up from across the table and said, “Do you mean, Hardy, if I said that two and two make five that you could prove any other proposition you like?” Hardy said, “Yes, I think so.” “Well, then, prove that McTaggart is the Pope.” “Well,” said Hardy, “if two and two make five, then five is equal to four. If you subtract three, you will find that two is equal to one. McTaggart and the Pope are two; therefore, McTaggart and the Pope are one.” I gather it came rather quickly.

[Quoted by Ronald Aylmer Fisher in his 1958 paper című The nature of probability.]