Henri Poincare
 JULES HENRI POINCARÉ  Macroknow Library

The Value of Science: Essential Writings of Henri Poincaré.


"Experiment is the sole source of truth. It alone can teach us something new; it alone can give us certainty. . . However, . . . It is not sufficient merely to observe; we must use our observations, and for that purpose we must generalize."1a PLANCK

"The man of science must work with method. Science is built up of facts, as a house is built of stones; but an accumulation of facts is no more a science than a heap of stones is a house. Most important of all, the man of science must exhibit foresight."1b


"But if science is feared, it is above all because it cannot give us happiness."1c

" . . . [W]hence does space get its quantitative character? It comes from the role which the series of muscular sensations play in its genesis. These are series which may repeat themselves, and it is from this repetition that that number comes; it is because they can repeat themselves indefinitely that space is infinite. . . So it is repetition which has given to space its essential characteristics; now, repetition supposes time; this is enough to tell that time is logically anterior to space."1d*

"Now what is science? . . . it is before all a classification, a manner of bringing together facts which appearances separate, though they were bound together by some natural and hidden kinship. Science, in other words, is a system of relations."1e PLANCK HEIDEGGER BADIOU


" . . . [T]he triumphs of industry, which have enriched so many practical men, would never have seen the light if only these practical men had existed, and if they had not been preceded by disinterested fools who died poor, who never thought of the useful, and yet had a guide that was not their own caprice."1f MARX PASTEUR CARNEGIE SCHUMPETER GHANDI HEIDEGGER

" . . . [H]istory does not repeat itself . . ."1g NIETZSCHE

"The scientist does not study nature because it is useful to do so. He studies it because he takes pleasure in it, and he takes pleasure in it because it is beautiful."1h

"How does it happen that there are people who do not understand mathematics? . . .
A mathematical demonstration is not a simple juxtaposition of syllogisms; it consists of syllogisms placed in a certain order, and the order in which these elements are placed is much more important than the elements themselves. . .
. . . this feeling, this intuition of mathematical order, which enables us to guess hidden harmonies and relations, cannot belong to everyone."

"Discovery is discernment, selection."1j

"It is not enough to feel doubts about everything; we must know why we doubt."1k


* Italics in the original.

1 Henri Poincaré (1854-1912). The Value of Science: Essential Writings of Henri Poincaré. Stephen Jay Gould, Series Editor. Biographical note and compilation, Random House, Inc., 2001. Series introduction, Stephen Jay Gould, 2001. New York, NY: Modern Library.
a Part IV: Chapter X: The Theories of Modern Physics, at 109.
b Ibid., at 110.
c Introduction, at 190.
d Part I: Chapter IV: Space and Its Three Dimensions, at 266.
e Part III: Chapter XI: Science and Reality, at 347.
f Part I: Chapter I: The Selection of Facts, at 364.
Ibid., at 366.
h Ibid., at 368
i Part I: Chapter III: Mathematical Discovery, at 387-390.
j Ibid., at 390.
k Part II: Chapter II: Mathematical Definitions and Education, at 449.