Because they played a major role in enthehaseracism which led to major ethnicity and public advances including more tourism
The Lord gave the Vassal a fief. The Vassal pledged their allegiance to the lord.
The Lord gave the Serf protection.
The Serf provided labor (farming and repairs).
It was primary imperialism that influenced the reform movements of the 1800s, since many Europeans thought it was morally wrong for imperialists to be exploiting native populations, mostly in South America and Africa.
He thought the business cycle would correct itself