The Importance of Springs in Human History

Chapters are not just about the inventions themselves, they also talk a lot about what they enable and what we built out of them. For example, in the chapter about springs, you talkA lot about weapons, bows, crossbows, and then guns,. Then pivot to clocks, which also use springs and obviously all very influential things in history. Are there any rabbit holes that you wanted to go into but it ended up then being too much to include in the book? There was so, so many of those that I can't, I've almost forgotten because there were so many.