One sometimes finds what one is not looking for.

The unprepared mind cannot see the outstretched hand of opportunity.

(The discovery of penicillin) was a triumph of accident, a fortunate occurrence which happened while I was working on a purely academic bacteriological problem.

One sometimes finds what one is not looking for. When I woke up just after dawn on Sept. 28, 1928, I certainly didn’t plan to revolutionize all medicine by discovering the world’s first antibiotic, or bacteria killer. But I guess that was exactly what I did.

It is not difficult to make microbes resistant to penicillin in the laboratory by exposing them to concentrations not sufficient to kill them, and the same thing has occasionally happened in the body. The time may come when penicillin can be bought by anyone in the shops. Then there is the danger that the ignorant man may easily underdose himself and by exposing his microbes to non-lethal quantities of the drug make them resistant.

It was astonishing that for some considerable distance around the mould growth the staphococcal colonies were undergoing lysis. What had formerly been a well-grown colony was now a faint shadow of its former self...I was sufficiently interested to pursue the subject.

Penicillin sat on a shelf for ten years while I was called a quack.