"There are two kinds of people in the world, whom we might dub the jobholders and the enthusiasts. ...The majority of the kings and emperors were jobholders and so were many of the popes. ...Most of the creators in the field of art and religion, and many of them in the field of science, were enthusiasts. Now economic conditions may deeply affect the jobs and the jobholders, but they make little impression on the enthusiasts. ...the jobholders ...keep things going with enough continuity and smoothness; they are the builders of usages and customs, the defenders of morality and justice. ...the enthusiasts ...are the main instruments of change and progress; they are the real creators and troublemakers. The enthusiasts are the salt of the earth, but man cannot live by salt alone."

“Erudition without pedantry is as a rare as wisdom itself.”

“A deed happens in a definite place at a definite time, but if it be sufficiently great and pregnant, its virtue radiates everywhere in time and space.”

“It is childish to assume that science began in Greece; the Greek "miracle" was prepared by millenia of work in Egypt, Mesopotamia and possibly in other regions. Greek science was less an invention than a revival.”

“The ability of nonintelligent people to understand the most complicated mechanisms and to use them has always been to me a cause of astonishment: their inability to understand simple questions is even more astonishing. The general acceptance of simple ideas is difficult and rare, and yet it is only when simple, fundamental, ideas have been accepted that further progress becomes possible on a higher level.”

“… science is the most revolutionary force in the world.”

“The scientific books written in Arabic durng the Middle Ages were, for a few centuries, the main vehicle of the living science.”