"My only merit is that I did not discard the cultures at an early stage."

"The mould grew, and then I saw the clear space around it."

"The bacteriologist is a detective. He must follow every clue, however small."

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

"I play with microbes. There are, of course, many rules to this play...but when you have acquired knowledge and experience it is very pleasant to break the rules and to be able to find something nobody…"