When the Plague hits, some protection has to be invented

The Plague Doctor outfit we see here was, after all, really useful to save a doctor's life.

It is considered to have been invented in 1619 by the French Doctor Charles de Lorme.

The idea was to protect as much as possible the doctor from what the plague was coming from (they didn't know it was from rats' fleas, of course):

• protect the lungs from the "bad air" coming in, so it has to go through the long beak and any kind of perfumes and cleaning stuff inside
• protect the head and eyes with suitable heavy protection and goggles
• protect the hands with thick leather gloves, and the feet with suitable shoes
• protect the body with a slippery mantle, so whatever it was coming, it would not go inside
• provide some instrument to the doctor so he wouldn't have to get close to the sick, could pass orders around, and protect himself from the diseased relatives in case the patient had died and they would get mad at him. I'm not kidding.
• the hat was the common one doctors would use in any situation: wide brimmed leather hood to show that they were doctors

It may look like a weird costume, but it is, in the end, a quite modern and functional piece of kit.