"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."

"Nature makes penicillin; I just found it."

"The early days of penicillin were full of disappointments, but we never gave up."

"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."

"I have been working for many years on the problem of finding substances which would destroy microbes in the body without injuring the cells of the body."