"The mere fact that a substance has bactericidal powers does not mean that it can be used for the treatment of septic infections."

"The power of observation is crucial in scientific research."

"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…"

"My laboratory was always a bit chaotic, but I knew where everything was."

"If penicillin can cure those that are ill, Spanish sherry can bring the dead back to life."