"How fortunate we didn't have these animal tests in the 1940s, for penicillin would probably not have been granted a licence, and possibly the whole field of antibiotics might never have been realised."

"When I woke up just after dawn on September 28, 1928, I certainly didn’t plan to revolutionize all medicine by discovering the world’s first antibiotic, or bacteria killer, ... But I guess that was exactly what I did."

"I have been trying to point out that in our lives chance may have an astonishing influence and, if I may offer advice to the young laboratory worker, it would be this—never neglect an extraordinary appearance or happening. It may be—usually is, in fact—a false alarm that leads to nothing, but may on the other hand be the clue provided by fate to lead you to some important advance."

"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 the enterprise, thought, and perception of an individual."

"One sometimes finds what one is not looking for."