"I was not a great scientist, but I was a careful observer."

"The early days of penicillin were full of disappointments, but we never gave up."

"The mould was very interesting. I cultured it and found it produced a powerful antibacterial substance. It was very effective against staphylococci and other Gram-positive pathogenic bacteria."

"The story of penicillin has a certain romantic appeal, and I think that may be one of the reasons it has attracted so much attention. But the real story is much more prosaic."

"The story of penicillin has been told so often that it is almost a cliché."