The article looks at how wealth has changed over time in Western countries. It found that before World War I, there was less wealth inequality than previously thought. Wealth concentration has decreased in Europe but increased in the United States. Most wealth now belongs to regular people, not just the super-rich. The amount of money made from investments has stayed pretty steady, especially after World War II. This research suggests that policies supporting regular people in building wealth are important for how wealth changes in society over time.