"To be a scholar of mathematics you must be born with talent, insight, concentration, taste, drive and the ability to visualize and guess."

I Want to be a Mathematician, Washington: MAA Spectrum, 1985.
 

"When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong."

Albert Einstein (1879 - 1955), "Science, Philosophy and Religion: a Symposium", 1941