Answers with Explanation:
Emmanuel-Joseph Sieyes was a constitutional theorist who played a vital role in the "French Revolution." He was popularly known as "Abbe." He called for a radical restructuring of the French society because he argued that the noble people were fraudulent and that they oppressed the middle class (Bourgeoisie) and the peasants.
The Bourgeoisie and the peasants were part of the Third Estate, thus his views were more concerned on this group of people. He was able to outline the frustrations and complaints of the Third Estate and this, somehow, fueled the French Revolution. He wanted sovereignty to be placed in the hands of people who were primary contributors to public service, such as the Third Estate and not the aristocrats.