Henri Poincare
Henri Poincare
Jules Henri Poincaréwas a French mathematician, theoretical physicist, engineer, and a philosopher of science. He is often described as a polymath, and in mathematics as The Last Universalist by Eric Temple Bell, since he excelled in all fields of the discipline as it existed during his lifetime...
NationalityFrench
ProfessionMathematician
Date of Birth29 April 1854
CountryFrance
ideas imagination long
For a long time the objects that mathematicians dealt with were mostly ill-defined; one believed one knew them, but one represented them with the senses and imagination; but one had but a rough picture and not a precise idea on which reasoning could take hold.
ideas one-day different
I then began to study arithmetical questions without any great apparent result, and without suspecting that they could have the least connexion with my previous researches. Disgusted at my want of success, I went away to spend a few days at the seaside, and thought of entirely different things. One day, as I was walking on the cliff, the idea came to me, again with the same characteristics of conciseness, suddenness, and immediate certainty, that arithmetical transformations of indefinite ternary quadratic forms are identical with those of non-Euclidian geometry.
ideas feet way
I entered an omnibus to go to some place or other. At that moment when I put my foot on the step the idea came to me, without anything in my former thoughts seeming to have paved the way for it, that the transformations I had used to define the Fuchsian functions were identical with non-Euclidean geometry.
ideas long mind
Often when works at a hard question, nothing good is accomplished at the first attack. Then one takes a rest, long or short, and sits down anew to the work. During the first half-hour, as before, nothing is found, and then all of a sudden the decisive idea presents itself to the mind.
men ideas example
It is often said that experiments should be made without preconceived ideas. That is impossible. Not only would it make every experiment fruitless, but even if we wished to do so, it could not be done. Every man has his own conception of the world, and this he cannot so easily lay aside. We must, example, use language, and our language is necessarily steeped in preconceived ideas. Only they are unconscious preconceived ideas, which are a thousand times the most dangerous of all.
business ideas clouds
Ideas rose in clouds; I felt them collide until pairs interlocked, so to speak, making a stable combination.
means necessary neither nor
Thus, be it understood, to demonstrate a theorem, it is neither necessary nor even advantageous to know what it means . . . .
american-journalist governed phenomenon succeeding
If that enabled us to predict the succeeding situation with the same approximation, that is all we require, and we should say that the phenomenon had been predicted, that it is governed by the laws.
avoiding consists infinite invention useful useless
Invention consists in avoiding the constructing of useless contraptions and in constructing the useful combinations which are in infinite minority. To invent is to discern, to choose.
american-journalist cannot cause determines due effect escapes notice
A very small cause which escapes our notice determines a considerable effect that we cannot fail to see, and then we say that the effect is due to chance.
american-journalist believe both convenient equally necessity
To doubt everything, or, to believe everything, are two equally convenient solutions; both dispense with the necessity of reflection.
american-journalist species
It has adopted the geometry most advantageous to the species or, in other words, the most convenient.
american-journalist relations remain replace
Thus, they are free to replace some objects by others so long as the relations remain unchanged.
american-journalist
No more than these machines need the mathematician know what he does.