"A scientist is a man who tries to understand the world by experiment, and a philosopher is a man who tries to understand the world by thought."

"When we speak of the 'reality' of the external world, we mean that it is independent of our perception of it."

"The old pioneers of science, such as Galileo, Kepler, Newton, were deeply religious men."

"The true pioneer is a man who, if necessary, is prepared to go into the wilderness alone, without anyone following him."

"The true scientist is a man of faith."