In early modern Europe, the 'Estates' were a theoretical division of a country's population, and the 'Third Estate' referred to the mass of normal, everyday people. They played a vital role in the early days of the French Revolution, which also ended the common use of the division.

Members of the Third Estate were led by Mirabeau and Abbe Sieyes.

Explanation:
The Third Estate was the largest and most diverse social group in French society during the late 18th century. It included the commoners, such as peasants, artisans, and the bourgeoisie. This group was heavily burdened by taxes and faced many social and economic inequalities.

1. Mirabeau:
Mirabeau, also known as Honoré Gabriel Riqueti, was a prominent figure in the French Revolution. He belonged to the nobility but sympathized with the grievances of the Third Estate. Mirabeau was a skilled orator and used his influence to advocate for the rights of the common people. He played a crucial role in the early stages of the revolution, especially during the Estates-General and the National Assembly.

2. Abbe Sieyes:
Abbe Sieyes, whose full name was Emmanuel Joseph Sieyes, was a clergyman and a leading political thinker of the French Revolution. He was a member of the First Estate (clergy) but aligned himself with the cause of the Third Estate. Sieyes is famous for his pamphlet "What is the Third Estate?" published in 1789. In this pamphlet, he argued that the Third Estate was the true representative of the nation and should have more political power. His ideas greatly influenced the revolutionary movement and the formation of the National Assembly.

Both Mirabeau and Abbe Sieyes played crucial roles in mobilizing the Third Estate and advocating for its rights and interests. They worked towards challenging the absolute power of the monarchy and establishing a more democratic system of government. Their leadership and influence were instrumental in shaping the French Revolution and the subsequent events that unfolded.

In conclusion, members of the Third Estate were led by Mirabeau and Abbe Sieyes, who were influential figures in the French Revolution and played significant roles in advocating for the rights of the common people.