In which John Green teaches you about disease, and the effects that disease has had in human history. Disease has been with man since the beginning, and it has shaped the way humans operate in a lot of ways. John will teach you about the Black Death, the Great Dying, and the modern medical revolution that has changed the world. You can directly support Crash Course at https://www.patreon.com/crashcourse Subscribe for as little as $0 to keep up with everything we're doing. Free is nice, but if you can afford to pay a little every month, it really helps us to continue producing this content.