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Quotation of the day

The archive

Each day the home page sets out one sentence from mathematics, the philosophy of science, the psychology of learning and of growth, or literature, with its source. Here every day’s quotation is kept, from 4 October 2026, the newest first. Below it stands the whole collection, sixty-four quotations by fifty-two authors, each checked against its source, with a note on the text.

Day by day

A quotation tied to a date, a birthday, a lecture or a letter, is shown on that date, with a line saying why; on other days the collection is read through in turn. The list grows by one each day.

  1. “For the things we have to learn before we can do them, we learn by doing them.”

    AristotleNicomachean Ethics, II.1; tr. W. D. Ross
  2. “It is true that Fourier had the opinion that the principal aim of mathematics was public utility and explanation of natural phenomena; but a philosopher like him should have known that the sole end of science is the honor of the human mind, and that under this title a question about numbers is worth as much as a question about the system of the world.”

    C. G. J. JacobiLetter to A.-M. Legendre, 2 July 1830

The collection

Arranged by author. Each quotation is given with its source, and with a note on the text: the words of the original, where it was found, or what was left out. New quotations join the collection as they are found and checked.

  1. N. H. Abel

    “It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils.”

    A note in his notebook, Paris, 1826English as in O. Ore, Niels Henrik Abel (1957); French: il faut étudier les maîtres et non pas les écoliers.Shown each year on 5 August.
  2. Archimedes

    “Give me a place to stand on, and I can move the earth.”

    As reported by Pappus of Alexandria, Collection, Book VIII; tr. T. L. HeathHeath, The Works of Archimedes (1897), p. xix.
  3. Aristotle

    “For the things we have to learn before we can do them, we learn by doing them.”

    Nicomachean Ethics, II.1; tr. W. D. Ross1103a32–34.
  4. V. I. Arnold

    “Mathematics is the part of physics where experiments are cheap.”

    ‘On teaching mathematics’, Palais de la Découverte, Paris, 7 March 1997Russian Math. Surveys 53:1 (1998); third sentence of the text.Shown each year on 12 June.
  5. Francis Bacon

    “Reading maketh a full man; conference a ready man; and writing an exact man.”

    ‘Of Studies’, Essays, 1625Birth date Old Style.Shown each year on 22 January.
  6. Jerome Bruner

    “We begin with the hypothesis that any subject can be taught effectively in some intellectually honest form to any child at any stage of development.”

    The Process of Education, 1960Opening sentence of ch. 3, ‘Readiness for Learning’.Shown each year on 1 October.
  7. Georg Cantor

    “In mathematics the art of proposing a question must be held of higher value than solving it.”

    Thesis defended with his doctorate, Berlin, 1867In re mathematica ars proponendi quaestionem pluris facienda est quam solvendi (Thesis III).Shown each year on 3 March.
  8. J. A. Comenius

    “Let the main object of this, our Didactic, be as follows: To seek and to find a method of instruction, by which teachers may teach less, but learners may learn more; by which schools may be the scene of less noise, aversion, and useless labour, but of more leisure, enjoyment, and solid progress.”

    The Great Didactic, 1657; tr. M. W. KeatingeStatement of aim on the title page; the sentence continues after a semicolon.Shown each year on 28 March.
  9. Richard Dedekind

    “In science nothing capable of proof ought to be accepted without proof.”

    Was sind und was sollen die Zahlen?, 1888, preface; tr. W. W. BemanOpening sentence of the preface to the first edition.Shown each year on 6 October.
  10. René Descartes

    “It is not enough to have a good mind; the main thing is to apply it well.”

    Discourse on the Method, 1637, Part One; tr. J. Cottingham, R. Stoothoff and D. MurdochThe sentence opens ‘For’.Shown each year on 31 March.
  11. P. A. M. Dirac

    “It is more important to have beauty in one’s equations than to have them fit experiment.”

    ‘The Evolution of the Physicist’s Picture of Nature’, Scientific American, 1963Clause of a longer sentence opening ‘I think there is a moral to this story, namely that …’.
  12. F. M. Dostoevsky

    “Above all, don’t lie to yourself. The man who lies to himself and listens to his own lie comes to such a pass that he cannot distinguish the truth within him, or around him, and so loses all respect for himself and for others. And having no respect he ceases to love.”

    The Brothers Karamazov, Book II, ch. 2; tr. C. GarnettThe elder Zosima speaks. Garnett’s text (1912), checked 4 October 2026: she wrote ‘comes to such a pass’, not ‘comes to a point’, as the line is often quoted.Shown each year on 11 November.

    “Talk nonsense, but talk your own nonsense, and I’ll kiss you for it. To go wrong in one’s own way is better than to go right in someone else’s.”

    Crime and Punishment, Part III, ch. 1; tr. C. GarnettRazumihin speaks; Garnett’s text (1914), checked 4 October 2026.

    “For the secret of man’s being is not only to live but to have something to live for.”

    The Brothers Karamazov, Book V, ch. 5, ‘The Grand Inquisitor’; tr. C. GarnettGarnett’s text (1912), checked 4 October 2026.
  13. Euclid

    “There is no royal road to geometry.”

    To Ptolemy I, as reported by Proclus, Commentary on the First Book of Euclid’s ElementsReported speech in Proclus (tr. Morrow, p. 57).
  14. Michael Faraday

    “Nothing is too wonderful to be true, if it be consistent with the laws of nature; and in such things as these, experiment is the best test of such consistency.”

    Laboratory notebook, 19 March 1849Bence Jones, Life and Letters of Faraday (1870), II, 253.Shown each year on 19 March.
  15. Richard Feynman

    “The first principle is that you must not fool yourself—and you are the easiest person to fool.”

    ‘Cargo Cult Science’, Caltech, 1974Engineering and Science 37 (1974); Caltech text.Shown each year on 11 May.
  16. Viktor E. Frankl

    “Everything can be taken from a man but one thing: the last of the human freedoms—to choose one’s attitude in any given set of circumstances, to choose one’s own way.”

    Man’s Search for Meaning, Part One; tr. I. LaschBeacon Press text, checked 4 October 2026; in the book the words follow ‘they offer sufficient proof that’.Shown each year on 26 March.

    “Ultimately, man should not ask what the meaning of his life is, but rather must recognize that it is he who is asked. In a word, each man is questioned by life; and he can only answer to life by answering for his own life.”

    Man’s Search for Meaning, Part Two; tr. I. LaschBeacon Press text, checked 4 October 2026.

    “When we are no longer able to change a situation … we are challenged to change ourselves.”

    Man’s Search for Meaning, Part Two; tr. I. LaschBeacon Press text, checked 4 October 2026; the ellipsis leaves out ‘—just think of an incurable disease such as inoperable cancer—’.
  17. Galileo Galilei

    “Philosophy is written in this grand book, the universe, which stands continually open to our gaze. … It is written in the language of mathematics, and its characters are triangles, circles, and other geometric figures without which it is humanly impossible to understand a single word of it; without these, one wanders about in a dark labyrinth.”

    The Assayer, 1623; tr. S. DrakeDrake, Discoveries and Opinions of Galileo (1957), pp. 237–238; one sentence omitted.Shown each year on 15 February.
  18. C. F. Gauss

    “Truly, it is not knowledge but learning, not possessing but acquiring, not being there but getting there, that grants the greatest enjoyment.”

    Letter to Farkas Bolyai, 2 September 1808Close rendering of the German (Wahrlich es ist nicht das Wissen, sondern das Lernen …); Dunnington (1955) gives a looser two-part version.Shown each year on 30 April.

    “Pauca sed matura: few, but ripe.”

    His mottoOn his seal, a tree bearing few fruits.
  19. Paul Halmos

    “The best way to learn is to do; the worst way to teach is to talk.”

    ‘The Problem of Learning to Teach’, American Mathematical Monthly, 1975Amer. Math. Monthly 82 (1975), Part I.
  20. G. H. Hardy

    “Beauty is the first test: there is no permanent place in the world for ugly mathematics.”

    A Mathematician’s Apology, 1940, §10Verified against the text of §10.Shown each year on 7 February.

    “They must be true because, if they were not true, no one would have had the imagination to invent them.”

    Of formulae in Ramanujan’s first letter; ‘The Indian Mathematician Ramanujan’, 1937Amer. Math. Monthly 44 (1937); Ramanujan: Twelve Lectures (1940), p. 9.Shown each year on 22 December.

    “A mathematician, like a painter or a poet, is a maker of patterns. If his patterns are more permanent than theirs, it is because they are made with ideas.”

    A Mathematician’s Apology, 1940, §10Opening sentences of §10.
  21. David Hilbert

    “A mathematical problem should be difficult in order to entice us, yet not completely inaccessible, lest it mock at our efforts.”

    ‘Mathematical Problems’, International Congress of Mathematicians, Paris, 1900; tr. M. W. NewsonBull. AMS 8 (1902); lecture of 8 August 1900.Shown each year on 8 August.

    “We must know. We shall know.”

    Wir müssen wissen. Wir werden wissen. Address at Königsberg, 8 September 1930Closing words of ‘Naturerkennen und Logik’; inscribed on his grave.Shown each year on 8 September.
  22. C. G. J. Jacobi

    “It is true that Fourier had the opinion that the principal aim of mathematics was public utility and explanation of natural phenomena; but a philosopher like him should have known that the sole end of science is the honor of the human mind, and that under this title a question about numbers is worth as much as a question about the system of the world.”

    Letter to A.-M. Legendre, 2 July 1830Gesammelte Werke I (1881), 454–455; English as in N. Rose, Mathematical Maxims and Minims (1988), quoted on MacTutor, which has ‘honor’, checked 5 October 2026.Shown each year on 2 July.
  23. William James

    “No reception without reaction, no impression without correlative expression—this is the great maxim which the teacher ought never to forget.”

    Talks to Teachers on Psychology, 1899Ch. V, ‘The Necessity of Reactions’.Shown each year on 11 January.
  24. C. G. Jung

    “Your vision will become clear only when you can look into your own heart. Without, everything seems discordant; only within does it coalesce into unity. Who looks outside dreams; who looks inside awakes.”

    Letter to Fanny Bowditch, 22 October 1916; Letters, vol. 1; tr. R. F. C. HullLetters, vol. 1 (1973), p. 33, checked 4 October 2026; in the letter the first sentence begins ‘But your vision …’.Shown each year on 22 October.

    “One does not become enlightened by imagining figures of light, but by making the darkness conscious. The latter procedure, however, is disagreeable and therefore not popular.”

    ‘The Philosophical Tree’, 1945; Collected Works, vol. 13, para. 335; tr. R. F. C. HullAlchemical Studies, para. 335, checked 4 October 2026.

    “The creation of something new is not accomplished by the intellect but by the play instinct acting from inner necessity. The creative mind plays with the objects it loves.”

    Psychological Types, 1921, para. 197; tr. H. G. Baynes, rev. R. F. C. HullCollected Works, vol. 6, para. 197, checked 4 October 2026.Shown each year on 26 July.
  25. Sofia Kovalevskaya

    “Many who have never had an opportunity of knowing any more about mathematics confound it with arithmetic, and consider it an arid science. In reality, however, it is a science which requires a great amount of imagination, and one of the leading mathematicians of our century states the case quite correctly when he says that it is impossible to be a mathematician without being a poet in soul.”

    Letter to A. S. Shabelskaya, 1890; tr. I. F. HapgoodThe mathematician she quotes is usually taken to be Weierstrass.Shown each year on 15 January.
  26. Leopold Kronecker

    “God made the integers; all else is the work of man.”

    As reported by H. Weber, 1893Die ganzen Zahlen hat der liebe Gott gemacht, alles andere ist Menschenwerk.Shown each year on 7 December.
  27. P.-S. Laplace

    “Read Euler, read Euler, he is the master of us all.”

    As reported by G. Libri, Journal des Savants, 1846Lisez Euler, lisez Euler, c’est notre maître à tous.
  28. G. W. Leibniz

    “Music is a hidden arithmetic exercise of the soul, which does not know that it is counting.”

    Letter to Christian Goldbach, 17 April 1712Musica est exercitium arithmeticae occultum nescientis se numerare animi.Shown each year on 1 July.
  29. J. E. Littlewood

    “A good mathematical joke is better, and better mathematics, than a dozen mediocre papers.”

    A Mathematician’s Miscellany, 1953Introduction.Shown each year on 9 June.
  30. Ada Lovelace

    “We may say most aptly, that the Analytical Engine weaves algebraical patterns just as the Jacquard-loom weaves flowers and leaves.”

    Note A to her translation of Menabrea’s Sketch of the Analytical Engine, 1843Scientific Memoirs 3 (1843).Shown each year on 10 December.
  31. James Clerk Maxwell

    “The true Logic for this world is the Calculus of Probabilities.”

    Letter to Lewis Campbell, 1850Campbell and Garnett, Life of Maxwell (1882), p. 143; the sentence opens ‘Therefore’ and continues with a relative clause.Shown each year on 13 June.
  32. Peter Medawar

    “If politics is the art of the possible, research is surely the art of the soluble.”

    New Statesman, 19 June 1964Review of Koestler’s The Act of Creation; reprinted in The Art of the Soluble (1967).Shown each year on 28 February.
  33. Maryam Mirzakhani

    “The beauty of mathematics only shows itself to more patient followers.”

    Interview, Clay Mathematics Institute, 2008CMI Annual Report 2008.Shown each year on 12 May.
  34. Isaac Newton

    “If I have seen further it is by standing on ye sholders of Giants.”

    Letter to Robert Hooke, 5 February 1675/6Original spelling; Correspondence I (1959), 416. Date Old Style.Shown each year on 5 February.
  35. Emmy Noether

    “My methods are really methods of working and thinking; this is why they have crept in everywhere anonymously.”

    Letter to Helmut Hasse, 12 November 1931Meine Methoden sind Arbeits- und Auffassungsmethoden, und daher anonym überall eingedrungen.Shown each year on 23 March.
  36. Blaise Pascal

    “People are generally better persuaded by the reasons which they have themselves discovered than by those which have come into the mind of others.”

    Pensées, 10; tr. W. F. TrotterBrunschvicg numbering, as in Trotter.Shown each year on 19 June.
  37. Louis Pasteur

    “In the fields of observation chance favours only the prepared mind.”

    Address at Douai, 7 December 1854Dans les champs de l’observation le hasard ne favorise que les esprits préparés.Shown each year on 27 December.
  38. Jean Piaget

    “The principal goal of education is to create men who are capable of doing new things, not simply of repeating what other generations have done—men who are creative, inventive, and discoverers.”

    As reported by Eleanor Duckworth, ‘Piaget Rediscovered’, 1964Spoken remarks, 1964 conferences at Cornell and Berkeley; J. Res. Sci. Teaching 2 (1964).Shown each year on 9 August.
  39. The Academy of Plato

    “Let no one ignorant of geometry enter.”

    An inscription said to have stood over its entrance; first recorded in late antiquityPhiloponus and Elias, 6th century; see Saffrey (1968).
  40. Plutarch

    “For the mind does not require filling like a bottle, but rather, like wood, it only requires kindling to create in it an impulse to think independently and an ardent desire for the truth.”

    On Listening to Lectures, 18; tr. F. C. BabbittMoralia 48C, Loeb 1927; verified on LacusCurtius.
  41. Henri Poincaré

    “It is by logic that we prove, but by intuition that we discover.”

    Science and Method, 1908; tr. F. MaitlandBook II, ch. II; French: c’est par la logique qu’on démontre, c’est par l’intuition qu’on invente.Shown each year on 29 April.

    “Science is built up with facts, as a house is with stones. But a collection of facts is no more a science than a heap of stones is a house.”

    Science and Hypothesis, 1902, ch. IX; tr. G. B. HalstedHalsted’s translation, in The Foundations of Science (1913); checked 4 October 2026.

    “Mathematics is the art of giving the same name to different things.”

    ‘The Future of Mathematics’, Science and Method, 1908; tr. F. MaitlandReported clause of ‘I think I have already said somewhere that …’.
  42. Michael Polanyi

    “We can know more than we can tell.”

    The Tacit Dimension, 1966Ch. 1, p. 4; clause of a longer sentence, italicized in the original.Shown each year on 11 March.
  43. George Pólya

    “A great discovery solves a great problem but there is a grain of discovery in the solution of any problem.”

    How to Solve It, 1945, prefaceOpening sentence of the preface to the first printing.Shown each year on 13 December.
  44. Karl Popper

    “Science must begin with myths, and with the criticism of myths.”

    Conjectures and Refutations, 1963Ch. 1, sec. VII; the sentence opens with ‘Thus’ and continues after a semicolon.Shown each year on 28 July.
  45. Santiago Ramón y Cajal

    “Consider the possibility that any man could, if he were so inclined, be the sculptor of his own brain, and that even the least gifted may, like the poorest land that has been well cultivated and fertilized, produce an abundant harvest.”

    Advice for a Young Investigator, preface to the second edition, 1898; tr. N. and L. W. SwansonThe sentence opens ‘Instead,’ (MIT Press 1999, p. xv).Shown each year on 1 May.
  46. Bertrand Russell

    “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.”

    ‘The Study of Mathematics’, 1907New Quarterly, November 1907; Mysticism and Logic (1918), ch. IV.Shown each year on 18 May.
  47. Seneca

    “The process is mutual; for men learn while they teach.”

    Moral Letters to Lucilius, 7.8; tr. R. M. GummereMutuo ista fiunt, et homines dum docent discunt.
  48. William P. Thurston

    “The measure of our success is whether what we do enables people to understand and think more clearly and effectively about mathematics.”

    ‘On proof and progress in mathematics’, 1994Bull. AMS 30 (1994), end of §1.Shown each year on 30 October.
  49. L. S. Vygotsky

    “What the child can do in cooperation today he can do alone tomorrow.”

    Thought and Language, ch. 6; tr. E. Hanfmann and G. VakarMIT Press 1962, p. 104; same wording in Kozulin’s 1986 revision.Shown each year on 17 November.
  50. Hermann Weyl

    “My work has always tried to unite the true with the beautiful and when I had to choose one or the other, I usually chose the beautiful.”

    As recalled by Freeman Dyson, Nature, 10 March 1956Wording as on MacTutor. The line ‘Logic is the hygiene …’ is not in Weyl’s 1946 article and is not used.Shown each year on 9 November.
  51. A. N. Whitehead

    “Civilization advances by extending the number of important operations which we can perform without thinking about them.”

    An Introduction to Mathematics, 1911Ch. V.
  52. Eugene Wigner

    “The miracle of the appropriateness of the language of mathematics for the formulation of the laws of physics is a wonderful gift which we neither understand nor deserve.”

    ‘The Unreasonable Effectiveness of Mathematics in the Natural Sciences’, 1960Comm. Pure Appl. Math. 13 (1960); first sentence of the final paragraph.