As I sat watching the Hàn river from Ngũ Hành Sơn I thought about the function of watchtowers and what affordances they offer to humans using very generic words. I think watchtowers ultimately are to help people know when to grab their tools. Or to remind them about the tools that they have. For instance, if a man on a watchtower did not warn the people then they would not be ready when they enemy attacked. But when the watchman alerted the people then they could run home and grab their stick or whatever.
Humans are pretty defenseless without tools and so the watchtower reminded people about the tools that they had. Maybe they already saw some animals or different tribes approaching but in that moment of shock they were unsure of what to do. It could be that they completely forgot about the new spear that they had crafted but the watchtower's unusual sounds could have reminded them.
This is all speculation but I think it is still a powerful idea. We often forget what tools we have. Maybe we are trying to learn a new tool. But it's hard! If we are used to typing `cd` to change to a different directory then how can we learn `z` to jump to a specific folder? It's a lot faster but how do we learn this new tool? We have to break from our automatic response and remind ourselves in that specific moment.
For example, I had to replace `cd` with a function which would only remind me to use z! After a few hours I had learned to use z occasionally. I can't use z for everything because new folders aren't in the index the z uses to jump to folders. But maybe I will need to combine cd and z into one command so that I will always remember that I have the capability to jump