Why were the 8000 warriors built?

Protection for the afterlife.

Hope this helps. :)

If referring to the ancient Chinese terracotta warriors, they were built to have protect the Emperor in his afterlife since it was thought an entire army was necessary to protect their Emperor with his over ranking position as their ruler.

Adam Smith is describing the system of Capitalism. Under capitalism you're free to establish and control your own business without being controlled by the government. As a consumer what you can buy is controlled by what businesses want to sell, not by what the government decides you should be able to buy. For example, under capitalism you have a lot of choices in cars. In a socialist system where the government controls the auto industry you have fewer choices. Fewer choices = less freedom.