In the 1890s, however, the Italian engineer-turned-economist Vilfredo Pareto stepped back from theoretical debate and searched for a pattern in the data. Having gathered income and tax records from England and from German states, from Paris and Italian towns, he plotted them on a graph and saw a curiously striking pattern emerge. In each case, he found, around 80% of national income was in the hands of just 20% of people,
The Pareto Principle was used to justify wealth inequality because it was a pattern seen across Europe
