Emmanuel Joseph Sieyès participant of French Revolution
Emmanuel Joseph Sieyès (3 May 1748 – 20 June 1836), usually known as the Abbé Sieyès (French: [sjejɛs]), was a French Roman Catholic abbé, clergyman, and political writer who was the chief political theorist of the French Revolution (1789–1799); he also held offices in the governments of the French Consulate (1799–1804) and the First French Empire (1804–1815). His pamphlet What Is the Third Estate? (1789) became the political manifesto of the Revolution, which facilitated transforming the Estates-General into the National Assembly, in June 1789. He was offered and refused an office in the French Directory (1795–1799). After becoming a director in 1799,  Sieyès was among the instigators of the Coup of 18 Brumaire (9 November), which installed Napoleon Bonaparte to power.
In addition to his political and clerical life, Sieyès coined the term "sociologie", and contributed to the nascent social sciences.Assemblies, Convention, and the Terror
Although not noted as a public speaker (he spoke rarely and briefly), Sieyès held major political influence, and he recommended the decision of the Estates to reunite its chamber as the National Assembly, although he opposed the abolition of tithes and the confiscation of Church lands. His opposition to the abolition of tithes discredited him in the National Assembly, and he was never able to regain his authority. Elected to the special committee on the constitution, he opposed the right of "absolute veto" for the King of France, which Honoré Mirabeau unsuccessfully supported. He had considerable influence on the framing of the departmental system, but, after the spring of 1790, he was eclipsed by other politicians, and was elected only once to the post of fortnightly president of the Constituent Assembly.Like all other members of the Constituent Assembly, he was excluded from the Legislative Assembly by the ordinance, initially proposed by Maximilien Robespierre, that decreed that none of its members should be eligible for the next legislature. He reappeared in the third national Assembly, known as the National Convention of the French Republic (September 1792 – September 1795). He voted for the death of Louis XVI, but not in the contemptuous terms sometimes ascribed to him. He participated to the Constitution Committee that drafted the Girondin constitutional project. Menaced by the Reign of Terror and offended by its character, Sieyès even abjured his faith at the time of the installation of the Cult of Reason; afterwards, when asked what he had done during the Terror, he famously replied, "J'ai vécu" ("I lived").Ultimately, Sieyès failed to establish the kind of bourgeois revolution he had hoped for, one of representative order "devoted to the peaceful pursuit of material comfort". His initial purpose was to instigate change in a more passive way, and to establish a constitutional monarchy. According to William Sewell, Sieyès' pamphlet set "the tone and direction of The French Revolution … but its author could hardly control the Revolution's course over the long run". Even after 1791, when the monarchy seemed to many to be doomed, Sieyès "continued to assert his belief in the monarchy", which indicated he did not intend for the Revolution to take the course it did.
During the period he served in the National Assembly, Sieyès wanted to establish a constitution that would guarantee the rights of French men and would uphold equality under the law as the social goal of the Revolution; he was ultimately unable to accomplish his goal.