The answer to this can be found in Chapter 14. There, Diamond gives us four ways in which elites could do this. He says that sometimes they used a mixture of the ways. Those ways were:
- Force. He says that the elites could make sure that only they had weapons. This made it easier for them to "convince" the others to give them some of the surplus.
- Keeping the people happy. If the elites took in the surplus but then gave it back out again, the people wouldn't really mind having their surplus taken.
- Maintain order. This is sort of a combination of the first two. If the elites used their weapons to make sure that no one was harming the people, this would make the people happier. They would not mind giving away their surplus because at least they were getting protection in return.
- Religion or ideology. Here, the elites would create or maintain some sort of tradition that claimed, for example, that the gods wanted them to rule. If the people believed that, then they would be okay with giving away their surplus because they would know that was what the gods wanted.