It's a fascinating question, and watch parts are a perfect catalyst for this topic. I imagine that it all started with a sun-dial... then intervals of time were derived, and once intervals were shown to be reliable and repeatable, an idea for a mechanism was born...

What I also like about this post, is how the photos capture the imperfections of the parts. We tend to think that time is perfect, but when you zoom in on the mechanism that keeps time, we realize how flawed of a tool it is..