Elliott Jaques was a man who studied how people work together and organized themselves. He wanted to understand how people become leaders and how different roles and jobs fit together in a big group or organization.
To understand this, he came up with a idea called "stratified systems theory." It's like building a tower of blocks, where each block is a different level of responsibility and skill. The bottom blocks are basic tasks that anyone can do, like cleaning or packing boxes. The blocks on top of those are a little harder, and might require more training or experience, like managing a small team. And then there are even higher blocks, where people are in charge of entire departments or even the whole organization.
Jaques believed that people had different natural abilities and were better suited for certain blocks in the tower. That means someone might be really good at managing a small team, but struggle if they were suddenly in charge of the entire organization.
He also thought that different levels in the tower required different levels of thinking ability. Someone in charge of a small team might need to be good at making quick decisions, while someone higher up in the tower would need to be good at thinking about big picture ideas and planning for the future.
Overall, Jaques thought that understanding this tower of blocks could help people work together more effectively, and make sure that everyone was in the right place for their skills and abilities.