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

"My own work was really quite simple. I just observed what was happening."

"We must be careful not to create a race of penicillin-resistant superbugs."

"I have been asked by many people how I came to discover penicillin. The answer is that I did not discover it. I just happened to notice it."

"The future of chemotherapy lies in the intelligent use of these new antibacterial agents."