1.John Snow was a well-known doctor in London–so famous，indeed，that he attended Queen Victoria to ease the birth of her babies.
2.But he became inspired when he thought about helping ordinary people exposed to cholera.
3.Neither its cause，nor its cure was understood.
4.He knew it would never be controlled until its cause was found.
5.He got interested in two theories explaining how cholera killed people.
6.The second suggested that people absorbed this disease into their bodies with their meals.
7.He believed in the second theory but needed to prove he was correct.
8.It seemed that the water was to blame.
9.Immediately John Snow told the astonished people in Broad Street to remove the handle from the water pump so it could not be used.
10.Only if you put the sun there did the movements of the other planets in the sky make sense.
11.But only his new theory could do that.
12.Yet Copernicus’theory is now the base on which all our ideas of the universe are built.