(CNN)By now, we've all heard this advice countless times: Wash your hands often and thoroughly, with soap and water.
It's one of the best weapons in our arsenal right now against the coronavirus.
Though washing our hands seems painfully obvious now, it wasn't always that way.
The importance of handwashing is thought to have been championed by Ignaz Semmelweis, a 19th century Hungarian obstetrician who worked in the maternity wards at the Vienna General Hospital.
Semmelweis' story is detailed in a 2013 article by Dana Tulodziecki, a philosophy professor at Purdue University. He's also the subject of Friday's Google Doodle.
How he made the discovery
The Vienna General Hospital had two maternity divisions, one staffed by doctors and another staffed by midwives. Semmelweis, who worked in the one staffed by doctors in the 1840's, noticed that new mothers were dying of a disease called childbed fever at higher rates in his division than they were in the one staffed by midwives.
So he set out to