"The public will not understand the dangers of using penicillin indiscriminately."

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

"It is not often that one finds a substance that is both highly bactericidal and non-toxic to animal tissues."

"I am only one of many who have contributed to the development of penicillin."

"I had no idea at the time that I was making a discovery that would change the course of medicine."