Why did Empress Wu support the civil service examination system?

Emperor Qin supported the exam system.

The system increased her personal wealth.

The system reduced the influence of the nobility class.

Empress Wu fought against the exam system.

Empress Wu supported the civil service examination system because: the system reduced the influence of the nobility class. She improved requirements and rules of participations in examination so that everyone deserving to be among those to own official positions could have such an opportunity. Being a wise empress, she also built many schools to train up potential scholars. She probably decided to change this system because she herself came from non-noble family so she thought that there were people like her.