Mystery is an inescapable ingredient of mathematics. Mathematics is full of unanswered questions, which far outnumber known theorems and results. It's the nature of mathematics to pose more problems than it can solve. Indeed, mathematics itself may be built on small islands of truth comprising the pieces of mathematics that can be validated by relatively short proofs. All else is speculation.

**Ivars Peterson**

mystery-is-inescapable-ingredient-mathematics-mathematics-is-full-unanswered-questions-which-far-outnumber-known-theorems-results-its-nature-ivars-peterson

If you ask ... the man in the street ... the human significance of mathematics, the answer of the world will be, that mathematics has given mankind a metrical and computatory art essential to the effective conduct of daily life, that mathematics admits of countless applications in engineering and the natural sciences, and finally that mathematics is a most excellent instrumentality for giving mental discipline... [A mathematician will add] that mathematics is the exact science, the science of exact thought or of rigorous thinking.

**Cassius Jackson Keyser**

if-you-ask-man-in-street-human-significance-mathematics-answer-world-will-be-that-mathematics-has-given-mankind-metrical-computatory-art-cassius-jackson-keyser

Mathematics has two faces: it is the rigorous science of Euclid, but it is also something else. Mathematics presented in the Euclidean way appears as a systematic, deductive science; but mathematics in the making appears as an experimental, inductive science. Both aspects are as old as the science of mathematics itself.

**George Polya**

mathematics-has-two-faces-it-is-rigorous-science-euclid-but-it-is-also-something-else-mathematics-presented-in-euclidean-way-appears-as-systematic-george-polya

Music can be appreciated from several points of view: the listener, the performer, the composer. In mathematics there is nothing analogous to the listener; and even if there were, it would be the composer, rather than the performer, that would interest him. It is the creation of new mathematics, rather than its mundane practice, that is interesting. Mathematics is not about symbols and calculations. These are just tools of the tradequavers and crotchets and five-finger exercises. Mathematics is about ideas. In particular it is about the way that different ideas relate to each other. If certain information is known, what else must necessarily follow? The aim of mathematics is to understand such questions by stripping away the inessentials and penetrating to the core of the problem. It is not just a question of getting the right answer; more a matter of understanding why an answer is possible at all, and why it takes the form that it does. Good mathematics has an air of economy and an element of surprise. But, above all, it has significance.

**Ian Stewart**

music-can-be-appreciated-from-several-points-view-listener-performer-composer-in-mathematics-there-is-nothing-analogous-to-listener-even-if-there-were-it-would-be-composer-rather

Srinivasa Ramanujan was the strangest man in all of mathematics, probably in the entire history of science. He has been compared to a bursting supernova, illuminating the darkest, most profound corners of mathematics, before being tragically struck down by tuberculosis at the age of 33... Working in total isolation from the main currents of his field, he was able to rederive 100 years' worth of Western mathematics on his own. The tragedy of his life is that much of his work was wasted rediscovering known mathematics.

**Michio Kaku**

srinivasa-ramanujan-was-strangest-man-in-all-mathematics-probably-in-entire-history-science-he-has-been-compared-to-bursting-supernova-michio-kaku

I don't want to convince you that mathematics is useful. It is, but utility is not the only criterion for value to humanity. Above all, I want to convince you that mathematics is beautiful, surprising, enjoyable, and interesting. In fact, mathematics is the closest that we humans get to true magic. How else to describe the patterns in our heads that - by some mysterious agency - capture patterns of the universe around us? Mathematics connects ideas that otherwise seem totally unrelated, revealing deep similarities that subsequently show up in nature.

**Ian Stewart**

i-dont-want-to-convince-you-that-mathematics-is-useful-it-is-but-utility-is-not-only-criterion-for-value-to-humanity-above-all-i-want-to-convince-you-ian-stewart

There is no thing as a man who does not create mathematics and yet is a fine mathematics teacher. Textbooks, course material-these do not approach in importance the communication of what mathematics is really about, of where it is going, and of where it currently stands with respect to the specific branch of it being taught. What really matters is the communication of the spirit of mathematics. It is a spirit that is active rather than contemplative-a spirit of disciplined search for adventures of the intellect. Only as adventurer can really tell of adventures.

**Alfred Adler**

there-is-no-thing-as-man-who-does-not-create-mathematics-yet-is-fine-mathematics-teacher-textbooks-course-materialthese-do-not-approach-in-alfred-adler

Most people have some appreciation of mathematics, just as most people can enjoy a pleasant tune; and there are probably more people really interested in mathematics than in music. Appearances suggest the contrary, but there are easy explanations. Music can be used to stimulate mass emotion, while mathematics cannot; and musical incapacity is recognized (no doubt rightly) as mildly discreditable, whereas most people are so frightened of the name of mathematics that they are ready, quite unaffectedly, to exaggerate their own mathematical stupidity

**G. H. Hardy**

most-people-have-some-appreciation-mathematics-just-as-most-people-can-enjoy-pleasant-tune-there-are-probably-more-people-really-interested-in-g-h-hardy

The broader the chess player you are, the easier it is to be competitive, and the same seems to be true of mathematics - if you can find links between different branches of mathematics, it can help you resolve problems. In both mathematics and chess, you study existing theory and use that to go forward.

**Viswanathan Anand**

the-broader-chess-player-you-are-easier-it-is-to-be-competitive-same-seems-to-be-true-mathematics-if-you-can-find-links-between-different-viswanathan-anand

music-is-mathematics-mathematics-listening-mathematics-for-ears-karlheinz-stockhausen

A chess problem is genuine mathematics, but it is in some way "trivial" mathematics. However, ingenious and intricate, however original and surprising the moves, there is something essential lacking. Chess problems are unimportant. The best mathematics is serious as well as beautiful-"important" if you like, but the word is very ambiguous, and "serious" expresses what I mean much better.

**G. H. Hardy**

a-chess-problem-is-genuine-mathematics-but-it-is-in-some-way-trivial-mathematics-however-ingenious-intricate-however-original-surprising-moves-g-h-hardy

Some people think that mathematics is a serious business that must always be cold and dry; but we think mathematics is fun, and we aren't ashamed to admit the fact. Why should a strict boundary line be drawn between work and play? Concrete mathematics is full of appealing patterns; the manipulations are not always easy, but the answers can be astonishingly attractive.

**Ronald Graham**

some-people-think-that-mathematics-is-serious-business-that-must-always-be-cold-dry-but-we-think-mathematics-is-fun-we-arent-ashamed-to-admit-fact-ronald-graham

[Mathematics] is security. Certainty. Truth. Beauty. Insight. Structure. Architecture. I see mathematics, the part of human knowledge that I call mathematics, as one thing-one great, glorious thing. Whether it is differential topology, or functional analysis, or homological algebra, it is all one thing... They are intimately interconnected, they are all facets of the same thing. That interconnection, that architecture, is secure truth and is beauty. That's what mathematics is to me.

**Paul R. Halmos**

mathematics-is-security-certainty-truth-beauty-insight-structure-architecture-i-see-mathematics-part-human-knowledge-that-i-call-mathematics-as-one-thingone-great-glorious-thing-

[Mathematics] is security. Certainty. Truth. Beauty. Insight. Structure. Architecture. I see mathematics, the part of human knowledge that I call mathematics, as one thing-one great, glorious thing. Whether it is differential topology, or functional analysis, or homological algebra, it is all one thing. ... They are intimately interconnected, they are all facets of the same thing. That interconnection, that architecture, is secure truth and is beauty. That's what mathematics is to me.

**Paul Halmos**

mathematics-is-security-certainty-truth-beauty-insight-structure-architecture-i-see-mathematics-part-human-knowledge-that-i-call-mathematics-as-one-paul-halmos

To criticize mathematics for its abstraction is to miss the point entirely. Abstraction is what makes mathematics work. If you concentrate too closely on too limited an application of a mathematical idea, you rob the mathematician of his most important tools: analogy, generality, and simplicity. Mathematics is the ultimate in technology transfer.

**Ian Stewart**

to-criticize-mathematics-for-its-abstraction-is-to-miss-point-entirely-abstraction-is-what-makes-mathematics-work-if-you-concentrate-too-closely-on-ian-stewart

You can keep counting forever. The answer is infinity. But, quite frankly, I don't think I ever liked it. I always found something repulsive about it. I prefer finite mathematics much more than infinite mathematics. I think that it is much more natural, much more appealing and the theory is much more beautiful. It is very concrete. It is something that you can touch and something you can feel and something to relate to. Infinity mathematics, to me, is something that is meaningless, because it is abstract nonsense.

**Doron Zeilberger**

you-can-keep-counting-forever-the-answer-is-infinity-but-quite-frankly-i-dont-think-i-ever-liked-it-i-always-found-something-repulsive-about-it-i-doron-zeilberger

Mathematics is much more than computation with pencil and a paper and getting answers to routine exercises. In fact, it can easily be argued that computation, such as doing long division, is not mathematics at all. Calculators can do the same thing and calculators can only calculate they cannot do mathematics.

**John A. Van de Walle**

mathematics-is-much-more-than-computation-with-pencil-paper-getting-answers-to-routine-exercises-in-fact-it-can-easily-be-argued-that-computation-john-a-van-de-walle

Like a stool which needs three legs to be stable, mathematics education needs three components: good problems, with many of them being multi-step ones, a lot of technical skill, and then a broader view which contains the abstract nature of mathematics and proofs. One does not get all of these at once, but a good mathematics program has them as goals and makes incremental steps toward them at all levels.

**Richard Askey**

like-stool-which-needs-three-legs-to-be-stable-mathematics-education-needs-three-components-good-problems-with-many-them-being-multistep-ones-lot-richard-askey

. . . the membership relation for sets can often be replaced by the composition operation for functions. This leads to an alternative foundation for Mathematics upon categories -- specifically, on the category of all functions. Now much of Mathematics is dynamic, in that it deals with morphisms of an object into another object of the same kind. Such morphisms (like functions) form categories, and so the approach via categories fits well with the objective of organizing and understanding Mathematics. That, in truth, should be the goal of a proper philosophy of Mathematics.

**Saunders Mac Lane**

membership-relation-for-sets-can-often-be-replaced-by-composition-operation-for-functions-this-leads-to-alternative-foundation-for-mathematics-saunders-mac-lane

Mathematics is the most exact science, and its conclusions are capable of absolute proof. But this is so only because mathematics does not attempt to draw absolute conclusions. All mathematical truths are relative, conditional. In E. T. Bell Men of Mathematics, New York: Simona and Schuster, 1937.

**Charles Proteus Steinmetz**

mathematics-is-most-exact-science-its-conclusions-are-capable-absolute-proof-but-this-is-only-because-mathematics-does-not-attempt-to-draw-charles-proteus-steinmetz

It is almost as hard to define mathematics as it is to define economics, and one is tempted to fall back on the famous old definition attributed to Jacob Viner, "Economics is what economists do," and say that mathematics is what mathematicians do. A large part of mathematics deals with the formal relations of quantities or numbers.

**Kenneth E. Boulding**

it-is-almost-as-hard-to-define-mathematics-as-it-is-to-define-economics-one-is-tempted-to-fall-back-on-famous-old-definition-attributed-to-jacob-kenneth-e-boulding

What is mathematics? Ask this question of person chosen at random, and you are likely to receive the answer "Mathematics is the study of number." With a bit of prodding as to what kind of study they mean, you may be able to induce them to come up with the description "the science of numbers." But that is about as far as you will get. And with that you will have obtained a description of mathematics that ceased to be accurate some two and a half thousand years ago!

**Keith Devlin**

what-is-mathematics-ask-this-question-person-chosen-at-random-you-are-likely-to-receive-answer-mathematics-is-study-number-with-bit-prodding-as-keith-devlin

The first and foremost duty of the high school in teaching mathematics is to emphasize methodical work in problem solving...The teacher who wishes to serve equally all his students, future users and nonusers of mathematics, should teach problem solving so that it is about one-third mathematics and two-thirds common sense.

**George Polya**

the-first-foremost-duty-high-school-in-teaching-mathematics-is-to-emphasize-methodical-work-in-problem-solvingthe-teacher-who-wishes-to-serve-george-polya

...mathematics is distinguished from all other sciences except only ethics, in standing in no need of ethics. Every other science, even logic, especially in its early stages, is in danger of evaporating into airy nothingness, degenerating, as the Germans say, into an arachnoid film, spun from the stuff that dreams are made of. There is no such danger for pure mathematics; for that is precisely what mathematics ought to be.

**Charles Sanders Peirce**

mathematics-is-distinguished-from-all-other-sciences-except-only-ethics-in-standing-in-no-need-ethics-every-other-science-even-logic-especially-in-charles-sanders-peirce

Statistics is, or should be, about scientific investigation and how to do it better, but many statisticians believe it is a branch of mathematics. Now I agree that the physicist, the chemist, the engineer, and the statistician can never know too much mathematics, but their objectives should be better physics, better chemistry, better engineering, and in the case of statistics, better scientific investigation. Whether in any given study this implies more or less mathematics is incidental.

**George E. P. Box**

statistics-is-should-be-about-scientific-investigation-how-to-do-it-better-but-many-statisticians-believe-it-is-branch-mathematics-now-i-agree-george-e-p-box

We had principles in mathematics that were granted to be absolute in mathematics for over 800 years, but new science has gotten rid of those absolutism, gotten forward other different logics of looking at mathematics, and sort of turned the way we look at it as a science altogether after 800 years.

**Mahmoud Ahmadinejad**

we-had-principles-in-mathematics-that-were-granted-to-be-absolute-in-mathematics-for-over-800-years-but-new-science-has-gotten-rid-those-absolutism-mahmoud-ahmadinejad

The point of mathematics is that in it we have always got rid of the particular instance, and even of any particular sorts of entities. So that for example, no mathematical truths apply merely to fish, or merely to stones, or merely to colours. So long as you are dealing with pure mathematics, you are in the realm of complete and absolute abstraction. . . . Mathematics is thought moving in the sphere of complete abstraction from any particular instance of what it is talking about.

**Alfred North Whitehead**

the-point-mathematics-is-that-in-it-we-have-always-got-rid-particular-instance-even-any-particular-sorts-entities-so-that-for-example-no-alfred-north-whitehead

This is a wonderful book, unique and engaging. Diaconis and Graham manage to convey the awe and marvels of mathematics, and of magic tricks, especially those that depend fundamentally on mathematical ideas. They range over many delicious topics, giving us an enchanting personal view of the history and practice of magic, of mathematics, and of the fascinating connection between the two cultures. Magical Mathematics will have an utterly devoted readership.

**Barry Mazur**

this-is-wonderful-book-unique-engaging-diaconis-graham-manage-to-convey-awe-marvels-mathematics-magic-tricks-especially-those-that-depend-barry-mazur

Mathematics never reveals man to the degree, never expresses him in the way, that any other field of human endeavour does: the extent of the negation of man's corporeal self that mathematics achieves cannot be compared with anything. Whoever is interested in this subject I refer to my articles. Here I will say only that the world injected its patterns into human language at the very inception of that language; mathematics sleeps in every utterance, and can only be discovered, never invented.

**Stanislaw Lem**

mathematics-never-reveals-man-to-degree-never-expresses-him-in-way-that-any-other-field-human-endeavour-does-extent-negation-mans-corporeal-stanislaw-lem

Mathematics alone make us feel the limits of our intelligence. For we can always suppose in the case of an experiment that it is inexplicable because we don't happen to have all the data. In mathematics we have all the data and yet we don't understand. We always come back to the contemplation of our human wretchedness. What force is in relation to our will, the impenetrable opacity of mathematics is in relation to our intelligence.

**Simone Weil**

mathematics-alone-make-us-feel-limits-our-intelligence-for-we-can-always-suppose-in-case-experiment-that-it-is-inexplicable-because-we-dont-simone-weil

These estimates may well be enhanced by one from F. Klein (1849-1925), the leading German mathematician of the last quarter of the nineteenth century. 'Mathematics in general is fundamentally the science of self-evident things.'... If mathematics is indeed the science of self-evident things, mathematicians are a phenomenally stupid lot to waste the tons of good paper they do in proving the fact. Mathematics is abstract and it is hard, and any assertion that it is simple is true only in a severely technical sense-that of the modern postulational method which, as a matter of fact, was exploited by Euclid. The assumptions from which mathematics starts are simple; the rest is not.

**Eric Temple Bell**

these-estimates-may-well-be-enhanced-by-one-from-f-klein-18491925-leading-german-mathematician-last-quarter-nineteenth-century-mathematics-in-general-is-fundamentally-science-sel

only-dead-mathematics-can-be-taught-where-competition-prevails-living-mathematics-must-always-be-communal-possession-mary-everest-boole

in-mathematics-i-can-report-no-deficiency-except-it-be-that-men-do-not-sufficiently-understand-excellent-use-pure-mathematics-francis-bacon

i-was-fortunate-to-find-extraordinary-mathematics-applied-mathematics-program-in-toronto

without-mathematics-your-world-becomes-foggy-for-clear-vision-you-need-to-be-educated-in-temple-mathematics-mehmet-murat-ildan

mathematics-knows-no-races-geographic-boundaries-for-mathematics-cultural-world-is-one-country

the-only-way-to-learn-mathematics-is-to-do-mathematics-that-tenet-is-foundation-doityourself-socratic-texas-method-paul-halmos

All our surest statements about the nature of the world are mathematical statements, yet we do not know what mathematics "is"... and so we find that we have adapted a religion strikingly similar to many traditional faiths. Change "mathematics" to "God" and little else might seem to change. The problem of human contact with some spiritual realm, of timelessness, of our inability to capture all with language and symbol-all have their counterparts in the quest for the nature of Platonic mathematics.

**John D. Barrow**

all-our-surest-statements-about-nature-world-are-mathematical-statements-yet-we-do-not-know-what-mathematics-is-we-find-that-we-have-adapted-john-d-barrow

we-in-science-are-spoiled-by-the-success-of-mathematics-mathematics-is-the-study-of-problems-so-simple-that-they-have-good-solutions

Eugene Wigner wrote a famous essay on the unreasonable effectiveness of mathematics in natural sciences. He meant physics, of course. There is only one thing which is more unreasonable than the unreasonable effectiveness of mathematics in physics, and this is the unreasonable ineffectiveness of mathematics in biology.

**Israel Gelfand**

eugene-wigner-wrote-famous-essay-on-unreasonable-effectiveness-mathematics-in-natural-sciences-he-meant-physics-course-there-is-only-one-thing-israel-gelfand

i-tell-you-that-studying-humanities-in-high-school-is-more-important-than-mathematics-mathematics-is-too-sharp-instrument-no-good-for-kids-stefan-banach

it-was-as-though-applied-mathematics-was-my-spouse-pure-mathematics-was-my-secret-lover-edward-frenkel

life-is-good-for-only-two-things-discovering-mathematics-teaching-mathematics-simeon-denis-poisson

Pure mathematics consists entirely of assertions to the effect that, if such and such a proposition is true of anything, then such and such another proposition is true of that thing. It is essential not to discuss whether the first proposition is really true, and not to mention what the anything is, of which it is supposed to be true. [... ] Thus mathematics may be defined as the subject in which we never know what we are talking about, nor whether what we are saying is true. People who have been puzzled by the beginnings of mathematics will, I hope, find comfort in this definition, and will probably agree that it is accurate.

**Bertrand Russell**

pure-mathematics-consists-entirely-assertions-to-effect-that-if-such-such-proposition-is-true-anything-then-such-such-another-proposition-is-true-that-thing-it-is-essential-not-t

Here is a quilted book about mathematical practice, each patch wonderfully prepared. Part invitation to number theory, part autobiography, part sociology of mathematical training, Mathematics without Apologies brings us into contemporary mathematics as a living, active inquiry by real people. Anyone wanting a varied, cultured, and penetrating view of today's mathematics could find no better place to engage.

**Peter Galison**

here-is-quilted-book-about-mathematical-practice-each-patch-wonderfully-prepared-part-invitation-to-number-theory-part-autobiography-part-sociology-peter-galison

formal-mathematics-is-natures-way-letting-you-know-how-sloppy-your-mathematics-is-leslie-lamport

The main duty of the historian of mathematics, as well as his fondest privilege, is to explain the humanity of mathematics, to illustrate its greatness, beauty and dignity, and to describe how the incessant efforts and accumulated genius of many generations have built up that magnificent monument, the object of our most legitimate pride as men, and of our wonder, humility and thankfulness, as individuals. The study of the history of mathematics will not make better mathematicians but gentler ones, it will enrich their minds, mellow their hearts, and bring out their finer qualities.

**George Sarton**

the-main-duty-historian-mathematics-as-well-as-his-fondest-privilege-is-to-explain-humanity-mathematics-to-illustrate-its-greatness-beauty-george-sarton

I do not remember having felt, as a boy, any passion for mathematics, and such notions as I may have had of the career of a mathematician were far from noble. I thought of mathematics in terms of examinations and scholarships: I wanted to beat other boys, and this seemed to be the way in which I could do so most decisively.

**G. H. Hardy**

i-do-not-remember-having-felt-as-boy-any-passion-for-mathematics-such-notions-as-i-may-have-had-career-mathematician-were-far-from-noble-i-g-h-hardy

Although some of her passages seek to persuade the reader of the meaninglessness and marginalization of the mathematics, Hayles is content to use mathematics as a means for understanding Borges, perhaps in the same way a sponge riddled with holes is useful in sopping up fluid reality.

**Bloch William Goldbloom**

although-some-her-passages-seek-to-persuade-reader-meaninglessness-marginalization-mathematics-hayles-is-content-to-use-mathematics-as-means-for-understanding-borges-perhaps-in-s

Roger Bacon, a disciple of the Arabs, also insisted on the primary necessity of Mathematics, without which no other science can be known; yet by Mathematics it is clear that he meant something very different from what we mean, including under that head even dancing, singing, gesticulation, and performance on musical instruments.

**George Henry Lewes**

roger-bacon-disciple-arabs-also-insisted-on-primary-necessity-mathematics-without-which-no-other-science-can-be-known-yet-by-mathematics-it-is-george-henry-lewes

A first fact should surprise us, or rather would surprise us if we were not used to it. How does it happen there are people who do not understand mathematics? If mathematics invokes only the rules of logic, such as are accepted by all normal minds...how does it come about that so many persons are here refractory?

**Henri Poincare**

a-first-fact-should-surprise-us-rather-would-surprise-us-if-we-were-not-used-to-it-how-does-it-happen-there-are-people-who-do-not-understand-henri-poincare

(1) Use mathematics as shorthand language, rather than as an engine of inquiry. (2) Keep to them till you have done. (3) Translate into English. (4) Then illustrate by examples that are important in real life (5) Burn the mathematics. (6) If you can't succeed in 4, burn 3. This I do often.

**Alfred Marshall**

1-use-mathematics-as-shorthand-language-rather-than-as-engine-inquiry-2-keep-to-them-till-you-have-done-3-translate-into-english-4-then-illustrate-by-examples-that-are-important-

people-think-that-mathematics-is-complicated-mathematics-is-simple-bit-its-stuff-we-can-understand-its-cats-that-are-complicated-john-horton-conway

mathematics-may-be-defined-as-economy-counting-there-is-no-problem-in-whole-mathematics-which-cannot-be-solved-by-direct-counting-ernst-mach

Mathematics is not something that you find lying around in your back yard. It's produced by the human mind. Yet if we ask where mathematics works best, it is in areas like particle physics and astrophysics, areas of fundamental science that are very, very far removed from everyday affairs.

**Paul Davies**

mathematics-is-not-something-that-you-find-lying-around-in-your-back-yard-its-produced-by-human-mind-yet-if-we-ask-where-mathematics-works-best-it-is-paul-davies

I'm not the sort of person who does my mathematics writing on paper. I do that at the last stage of the game. I do my mathematics in my head. I sit down for a hard day's work and I write nothing all day. I just think. And I walk up and down because that helps keep me awake, it keeps the blood circulating, and I think and think.

**Michael Atiyah**

im-not-sort-person-who-does-my-mathematics-writing-on-paper-i-do-that-at-last-stage-game-i-do-my-mathematics-in-my-head-i-sit-down-for-hard-days-michael-atiyah

Mathematics is not arithmetic. Though mathematics may have arisen from the practices of counting and measuring it really deals with logical reasoning in which theorems-general and specific statements-can be deduced from the starting assumptions. It is, perhaps, the purest and most rigorous of intellectual activities, and is often thought of as queen of the sciences.

**Christopher Zeeman**

mathematics-is-not-arithmetic-though-mathematics-may-have-arisen-from-practices-counting-measuring-it-really-deals-with-logical-reasoning-in-which-theoremsgeneral-specific-statem

Turing attended Wittgenstein's lectures on the philosophy of mathematics in Cambridge in 1939 and disagreed strongly with a line of argument that Wittgenstein was pursuing which wanted to allow contradictions to exist in mathematical systems. Wittgenstein argues that he can see why people don't like contradictions outside of mathematics but cannot see what harm they do inside mathematics. Turing is exasperated and points out that such contradictions inside mathematics will lead to disasters outside mathematics: bridges will fall down. Only if there are no applications will the consequences of contradictions be innocuous. Turing eventually gave up attending these lectures. His despair is understandable. The inclusion of just one contradiction (like 0 = 1) in an axiomatic system allows any statement about the objects in the system to be proved true (and also proved false). When Bertrand Russel pointed this out in a lecture he was once challenged by a heckler demanding that he show how the questioner could be proved to be the Pope if 2 + 2 = 5. Russel replied immediately that 'if twice 2 is 5, then 4 is 5, subtract 3; then 1 = 2. But you and the Pope are 2; therefore you and the Pope are 1'! A contradictory statement is the ultimate Trojan horse.

**John D. Barrow**

turing-attended-wittgensteins-lectures-on-philosophy-mathematics-in-cambridge-in-1939-disagreed-strongly-with-line-argument-that-wittgenstein-was-pursuing-which-wanted-to-allow-c

Mathematics is the art of explanation. If you deny students the opportunity to engage in this activity-- to pose their own problems, to make their own conjectures and discoveries, to be wrong, to be creatively frustrated, to have an inspiration, and to cobble together their own explanations and proofs-- you deny them mathematics itself.

**Paul Lockhart**

mathematics-is-art-explanation-if-you-deny-students-opportunity-to-engage-in-this-activity-to-pose-their-own-problems-to-make-their-own-conjectures-paul-lockhart