"The time may come when penicillin can be bought by anyone in the shops. Then there is the danger that the ignorant man may easily underdose himself and by exposing his microbes to non-lethal quantitie…"

"It is a popular misconception that I was a brilliant chemist, but I was not. I was a bacteriologist."

"The discovery of penicillin was a series of small observations, not a single eureka moment."

"It was not easy to convince people of the importance of penicillin in the early days."

"It is not difficult to make microbes resistant to penicillin in the laboratory by exposing them to concentrations not sufficient to kill them."