140 Quotes by Henri Poincare

". . . by natural selection our mind has adapted itself to the conditions of the external world. It has adopted the geometry most advantageous to the species or, in other words, the most convenient. Geometry is not true, it is advantageous."

"Hypotheses are what we lack the least."

"[T]he different branches of Arithmetic - Ambition [G]eometry is not true, it is advantageous."

"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?"

"To invent is to discern, to choose."

"A cat is witty, he has nerve, he knows how to do precisely the right thing at the right moment."

"It is with logic that one proves; it is with intuition that one invents."

"Talk with M. Hermite. He never evokes a concrete image, yet you soon perceive that the more abstract entities are to him like living creatures."

"We also know how cruel the truth often is, and we wonder whether delusion is not more consoling."

"Zero is the number of objects that satisfy a condition that is never satisfied. But as never means "in no case", I do not see that any progress has been made."