"I have never been able to believe in anything that I could not demonstrate by experiment."

"The true wealth of a nation is its knowledge and its industry."

"The chemist, like the artist, must have a vivid imagination, but it must be controlled by reason."

"I have been so lucky in life, that I have had nothing to do but to collect the fruits of the labours of others."

"The scientist should be a judge, not an advocate."