David Hilbert
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David Hilbert (January 23, 1862 – February 14, 1943) was a German mathematician recognized as one of the most influential and universal mathematicians of the 19th and early 20th centuries. He invented or developed a broad range of fundamental ideas, in invariant theory, the axiomatization of geometry, and with the notion of Hilbert space, one of the foundations of functional analysis.
Sourced[edit]
 Good, he did not have enough imagination to become a mathematician.
 Upon hearing that one of his students had dropped out to study poetry. (David J. Darling (2004). The Universal Book of Mathematics. John Wiley and Sons. p. 151. ISBN 9780471270478.)
 Aus dem Paradies, das Cantor uns geschaffen, soll uns niemand vertreiben können.
 No one shall expel us from the Paradise that Cantor has created.
 "Über das Unendliche" [On the Infinite] in Mathematische Annalen 95, (1926)
 No one shall expel us from the Paradise that Cantor has created.
 Wir dürfen nicht denen glauben, die heute mit philosophischer Miene und überlegenem Tone den Kulturuntergang prophezeien und sich in dem Ignorabimus gefallen. Für uns gibt es kein Ignorabimus, und meiner Meinung nach auch für die Naturwissenschaft überhaupt nicht. Statt des törichten Ignorabimus heiße im Gegenteil unsere Losung:

 Wir müssen wissen — wir werden wissen!
 We must not believe those, who today, with philosophical bearing and deliberative tone, prophesy the fall of culture and accept the ignorabimus. For us there is no ignorabimus, and in my opinion none whatever in natural science. In opposition to the foolish ignorabimus our slogan shall be:
 We must know — we will know!
 Address to the Society of German Scientists and Physicians, in Königsberg (8 September 1930). The concluding statement was used as the epitaph on his tomb in Göttingen. Radio broadcast of the address, and transcription and English translation.
 One can measure the importance of a scientific work by the number of earlier publications rendered superfluous by it.
 Quoted in Mathematical Circles Revisited (1971) by Howard Whitley Eves
 Mathematics knows no races or geographic boundaries; for mathematics, the cultural world is one country.
 Quoted in Mathematical Circles Revisited (1971) by Howard Whitley Eves
 "Mathematics is a presuppositionless science. To found it I do not need God, as does Kronecker, or the assumption of a special faculty of our understanding attuned to the principle of mathematical induction, as does Poincaré, or the primal intuition of Brouwer, or, finally, as do Russell and Whitehead, axioms of infinity, reducibility, or completeness, which in fact are actual, contentual assumptions that cannot be compensated for by consistency proofs.
 Quoted in Hilbert's Die Grundlagen der Mathematik (1927)
 If one were to bring ten of the wisest men in the world together and ask them what was the most stupid thing in existence, they would not be able to discover anything so stupid as astrology.
 Quoted in Comic Sections (1993) by Desmond MacHale
 If I were to awaken after having slept for a thousand years, my first question would be: Has the Riemann hypothesis been proven?
 Quoted in Mathematical Mysteries : The Beauty and Magic of Numbers (1999) by Calvin C. Clawson, p. 258
 One of the supreme achievements of purely intellectual human activity.
 On the Cantor set, as quoted in A World Without Time : The Forgotten Legacy of Godel and Einstein (2005) by Palle Yourgrau, p. 44
 But he (Galileo) was not an idiot,... Only an idiot could believe that scientific truth needs martyrdom — that may be necessary in religion, but scientific results prove themselves in time.
 Hilbert (2nd edition, 1996) by Constance Reid, p. 92
 Sometimes it happens that a man's circle of horizon becomes smaller and smaller, and as the radius approaches zero it concentrates on one point. And then that becomes his point of view.
 HilbertCourant (1984) by Constance Reid, p. 174
 Keep computations to the lowest level of the multiplication table.
 HilbertCourant (1984) by Constance Reid, p. 104
 Begin with the simplest examples.
 HilbertCourant (1984) by Constance Reid, p. 104
 I do not see that the sex of the candidate is an argument against her admission as a Privatdozent. After all, the Senate is not a bathhouse.
 HilbertCourant (1984) by Constance Reid, p. 143
 Every kind of science, if it has only reached a certain degree of maturity, automatically becomes a part of mathematics.
 Axiomatic Thought (1918), printed in from Kant to Hilbert, Vol. 2 by Ewald
Mathematical Problems (1900)[edit]
 History teaches the continuity of the development of science. We know that every age has its own problems, which the following age either solves or casts aside as profitless and replaces by new ones. If we would obtain an idea of the probable development of mathematical knowledge in the immediate future, we must let the unsettled questions pass before our minds and look over the problems which the science of today sets and whose solution we expect from the future. To such a review of problems the present day, lying at the meeting of the centuries, seems to me well adapted. For the close of a great epoch not only invites us to look back into the past but also directs our thoughts to the unknown future.
 A mathematical problem should be difficult in order to entice us, yet not completely inaccessible, lest it mock at our efforts. It should be to us a guide post on the mazy paths to hidden truths, and ultimately a reminder of our pleasure in the successful solution.
 It remains to discuss briefly what general requirements may be justly laid down for the solution of a mathematical problem. I should say first of all, this: that it shall be possible to establish the correctness of the solution by means of a finite number of steps based upon a finite number of hypotheses which are implied in the statement of the problem and which must always be exactly formulated. This requirement of logical deduction by means of a finite number of processes is simply the requirement of rigor in reasoning.
 To new concepts correspond, necessarily, new signs. These we choose in such a way that they remind us of the phenomena which were the occasion for the formation of the new concepts.
 If we do not succeed in solving a mathematical problem, the reason frequently consists in our failure to recognize the more general standpoint from which the problem before us appears only as a single link in a chain of related problems. After finding this standpoint, not only is this problem frequently more accessible to our investigation, but at the same time we come into possession of a method which is applicable also to related problems.
 This conviction of the solvability of every mathematical problem is a powerful incentive to the worker. We hear within us the perpetual call: There is the problem. Seek its solution. You can find it by pure reason, for in mathematics there is no ignorabimus.
 Mathematical science is in my opinion an indivisible whole, an organism whose vitality is conditioned upon the connection of its parts. For with all the variety of mathematical knowledge, we are still clearly conscious of the similarity of the logical devices, the relationship of the ideas in mathematics as a whole and the numerous analogies in its different departments. We also notice that, the farther a mathematical theory is developed, the more harmoniously and uniformly does its construction proceed, and unsuspected relations are disclosed between hitherto separate branches of the science. So it happens that, with the extension of mathematics, its organic character is not lost but only manifests itself the more clearly.
 The organic unity of mathematics is inherent in the nature of this science, for mathematics is the foundation of all exact knowledge of natural phenomena. That it may completely fulfil this high mission, may the new century bring it gifted masters and many zealous and enthusiastic disciples!
 An old French mathematician said: A mathematical theory is not to be considered complete until you have made it so clear that you can explain it to the first man whom you meet on the street. This clearness and ease of comprehension, here insisted on for a mathematical theory, I should still more demand for a mathematical problem if it is to be perfect; for what is clear and easily comprehended attracts, the complicated repels us.
 Eine mathematische Theorie ist nicht eher als vollkommen anzusehen, als bis du sie so klar gemacht hast, daß du sie dem ersten Manne erklären könntest, den du auf der Straße triffst.
Attributed[edit]
 Physics is too difficult for physicists!
 This quote has many variants. An early version attributed to the Göttingen School appears in a book review by Heinrich Wieleitner in Isis, Volume 7, No. 4, December 1925, p. 597: Ach, die Physik! Die ist ja für die Physiker viel zu schwer! (Oh, physics! That's just too difficult for the physicists!).