Most commonly known as the Abbé Sieyès, was a French Roman Catholic abbé, clergyman and political writer, Second Consul of France during Napoleonic era, one of the first members of what would become the Academy of Moral and Political Sciences of the Institute of France.
Abbé Sieyès was one of the chief political theorists of the French Revolution, and also played a prominent role in the French Consulate and First French Empire. His 1789 pamphlet What is the Third Estate? became the manifesto of the Revolution, helping to transform the Estates-General into the National Assembly in June 1789. In 1799, he was the instigator of the coup d'état of 18 Brumaire (9 November), which brought Napoleon Bonaparte to power. He also coined the term "sociologie" in an unpublished manuscript, and made significant theoretical contributions to the nascent social sciences.
Despite Sieyès' embrace of Enlightenment thinking, he was ordained to the priesthood in 1773. In spite of this, he was not hired immediately. He spent this time researching philosophy and developing music until about a year later in October 1774 when, as the result of demands by powerful friends, he was promised a canonry in Brittany. Unfortunately for Sieyès, this canonry went into effect only when the preceding holder died. At the end of 1775, Sieyès acquired his first real position as secretary to the bishop of Tréguier where he spent two years as deputy of the diocese. It is here that he sat in the Estates of Brittany and became disgusted with the immense power the privileged classes held. In 1780, the bishop of Tréguier was transferred to the bishopric of Chartres. He became aware of how easy it was for nobles to advance in ecclesiastical offices compared to commoners. Sieyes was an ambitious man; therefore, he resented the privileges granted to the nobles within the Church system and thought the patronage system was a humiliation for commoners. Sieyès accompanied him there as his vicar general where he eventually became a canon of the cathedral and chancellor of the diocese of Chartres.
While remaining in ecclesiastical offices, Sieyès maintained a religious cynicism at odds with his position. By the time he took his orders to enter priesthood, Sieyès had "freed himself from all superstitious sentiments and ideas." Even when corresponding with his deeply religious father, Sieyès showed a severe lack of piety for the man in charge of the diocese of Chartres.[8] It is theorised that Sieyes accepted a religious career not because he had any sort of strong religious inclination, but because he considered it the only means to advance his career as a political writer.