Ideas rose in clouds; I felt them collide until pairs interlocked, so to speak, making a stable combination.
Henri PoincarePure logic could never lead us to anything but tautologies; it can create nothing new; not from it alone can any science issue.
Henri PoincareGuessing before proving! Need I remind you that it is so that all important discoveries have been made?
Henri PoincareI 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.
Henri Poincare