What he had seen were two boys playing with a long board. One of them had his ear to one end while the other boy scratched the other end with a pin. The sound travels through the board, amplified along the way.

Later on, he was called to diagnose a young woman with apparent heart issues. Being reluctant to stick his ear to her chest, he remembered what he had seen and had an idea.

He rolled up a piece of paper into a tube and used it to listen to her heart. Surprised at how well it worked, he began designing a better model.

The stethoscope has gone through a few changes since his original design, but every doctor and nurse still uses it today. It is pretty much a symbol of the profession.

All from going on a walk and being observant.

Sometimes going for a walk and simply paying attention to your surroundings can lead to astonishing results. Luckily, he wasn’t staring at a TikTok video while he was walking.