In 1781, Condorcet wrote a pamphlet, Reflections on Negro Slavery, in which he denounced slavery. In 1786, Condorcet worked on ideas for the differential and integral calculus, giving a new treatment of infinitesimals – a work which was never printed. In 1789, he published Vie de Voltaire (1789), which agreed with Voltaire in his opposition to the Church. In 1791, Condorcet along with Sophie de Grouchy, Thomas Paine, Etienne Dumont, Jacques-Pierre Brissot, and Achilles Duchastellet published a brief journal titled Le Républicain. Its main goal being the promotion of republicanism and the rejection of establishing a constitutional monarchy. The theme being that any sort of monarchy is a threat to freedom no matter who is leading, which emphasized that liberty is freedom from domination.