The inside of the human body is dark and closed off—for the most part—from the world around it. This is usually an advantage. But when something goes wrong and surgeons believe they can fix it, they need to open up the body's barriers and see inside. The most obvious strategy—an incision long enough to give the doctor a clear view—comes with its own complications, which is why, for centuries, surgeons have been testing tools and techniques that allow them to see and work inside the human body without slicing it wide open.
It's only in the past 30 years, though, that they've actually gotten good at it.
At the most basic level, looking inside the human body might involve putting a tube in an existing hole to allow a little light in. Greek and Roman doctors made use of vaginal and anal specula. In the 1800s, one doctor inserted a tube into a urethra and used candlelight to try to get a better view. By the end of that century, after Edison produced his lightbulb, a Glasgow physician built a tiny bulb into a similar tube.
But it wasn't until the second half of the 20th century when fiber-optic threads brought brighter light into the caverns of the body. And later, tiny computer chip cameras started sending images back out. At last, doctors could not only clearly see inside a person's body without making a long incision, but could use tiny tools to perform surgery inside.