"If penicillin can cure those that are ill, Spanish sherry can bring the dead back to life."

"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."

"The mold was a lucky accident, but the observation was not."

"The most important thing in science is not to get discouraged by failures."

"Some people have been very enthusiastic about penicillin, others less so."