Geometry is the art of correct reasoning from incorrectly drawn figures.
Intuition is more important to discovery than logic.
Experiment is the sole source of truth. It alone can teach us something new; it alone can give us certainty.
It is far better to foresee even without certainty than not to foresee at all.
If we wish to foresee the future of mathematics, our proper course is to study the history and present condition of the science.
A cat is witty, he has nerve, he knows how to do precisely the right thing at the right moment.