"I had no idea that I would be involved in such a great discovery. It was purely accidental."

"The discovery of penicillin was a series of small observations, not a single eureka moment."

"I did not invent penicillin. Nature did. I just found it."

"I was just a dirty old man who left his dishes unwashed."

"I am sometimes asked what I think of the future of penicillin. I think it has a great future, but it must be used wisely."