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

"Many difficulties were encountered in the early attempts to isolate and purify penicillin."

"It is not the discovery of a new substance that is important, but the recognition of its properties."

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

"The unprepared mind cannot see the outstretched hand of opportunity."