Pure logic could never lead us to anything but tautologies; it can create nothing new; not from it alone can any science issue.
Henri PoincareExperiment is the sole source of truth. It alone can teach us something new; it alone can give us certainty.
Henri PoincareDeviner avant de démontrer! Ai-je besoin de rappeler que c'est ainsi que se sont faites toutes les découvertes importantes.
Henri PoincareIt 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.
Henri Poincare