For the birth of something new, there has to be a happening. Newton saw an apple fall; James Watt watched a kettle boil; Roentgen fogged some photographic plates. And these people knew enough to translate ordinary happenings into something new.

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

Nature makes penicillin; I just found it.

It is the lone worker who makes the first advance in a subject: the details may be worked out by a team, but the prime idea is due to the enterprise, thought, and perception of an individual.

I have been trying to point out that in our lives chance may have an astonishing influence and, if I may offer advice to the young laboratory worker, it would be this-never neglect an extraordinary appearance or happening. It may be-usually is, in fact-a false alarm that leads to nothing, but may on the other hand be the clue provided by fate to lead you to some important advance.

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 has thought of.

It has been demonstrated that a species of penicillium produces in culture a very powerful antibacterial substance which affects different bacteria in different degrees. Generally speaking it may be said that the least sensitive bacteria are the Gram-negative bacilli, and the most susceptible are the pyogenic cocci ... In addition to its possible use in the treatment of bacterial infections penicillin is certainly useful... for its power of inhibiting unwanted microbes in bacterial cultures so that penicillin insensitive bacteria can readily be isolated.