"A good many people think that I deserve some credit for the discovery of penicillin. They are wrong. It was discovered by nature."

"The story of penicillin is a lesson in serendipity and perseverance."

"The purification of penicillin was a major triumph of chemistry."

"Penicillin sat on my bench for ten years while I was called a quack."

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