Simplify the following text for a Grade 13 native English-speaking person.
Original: The book describes activities of the Roman Catholic clergy in the Kingdom of Yugoslavia , including their intention and attempts to become above the state , to control the state and eventually everyday lives of the common people .
Simplified: The book describes the activities of the Roman Catholic clergy in the Kingdom of Yugoslavia , including their intention and attempts to become above the state , to control the state and eventually the everyday lives of the common people .