"It is not difficult to make microbes resistant to penicillin in the laboratory by exposing them to concentrations not sufficient to kill them, and the same thing has occasionally happened in the body."

"My greatest satisfaction comes from knowing that my work has saved countless lives."

"I am not a hero. I just happened to be in the right place at the right time."

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

"It is the lone worker who makes the first advance in a subject; the details may be worked out by a team, but the prime idea is due to enterprise, thought, and perception of an individual."