How did a surgeon who read about fermentation make operations survivable?

Because he read about fermentation, drew a bold conclusion, and then worked out how to keep germs out of wounds. Joseph Lister, an English surgeon who became a pioneer of antiseptic surgery, started from a bleak situation. Despite the work of Ignaz Semmelweis and others, hospitals practised surgery under unsanitary conditions. Surgeons of the time referred to the "good old surgical stink" and took pride in the stains on their unwashed operating gowns as a display of their experience.

The turn came in conversation. While walking home with Thomas Anderson, the chemistry professor at Glasgow, Lister discussed putrefaction, and Anderson drew his attention to the research of the French chemist Louis Pasteur, who had discovered living things that caused fermentation and putrefaction. Lister was now convinced that infection and suppuration of wounds must be due to minute living airborne creatures entering the wound. He realised from the first that the surgeon's hands, dressings and instruments would also be contaminated.

That insight became a method. In 1865 Lister had success with carbolic acid on a compound fracture, in which a broken bone pushes through the skin and the standard treatment was amputation. The essential part of the treatment was not simply the strong acid on the wound, but a dressing designed to stop airborne infection getting in.

His ideas were widely criticised in his early career. But the numbers spoke: Lister reported that 16 of 35 patients died in the earlier period, against 6 of 40 after antiseptic treatment was introduced. In Germany, antiseptic methods were established faster than in any other developed country.