"I am not a very good speaker, but I hope my work speaks for itself."

"The discovery of penicillin was a stroke of luck, but it was also the result of many years of hard work."

"The scientist has to be a perpetual child, always asking 'Why?'"

"The therapeutic value of penicillin is enormous, but its indiscriminate use could lead to disaster."

"I had no idea that I would be involved in such a great discovery. It was purely accidental."