THOMAS, PIERRE (1634–1698), sieur du Fossé, French scholar and author, was the son of a master of accounts at Rouen. He was sent as a child to be educated at Port Royal, and there he received his final bent towards the life of a recluse, and even of a hermit, which drew him to establish himself in the neighbourhood of Port Royal des Champs. In 1661 he came to Paris, and in 1666 was arrested along with I. L. Le Maistre (de Sacy), and after a month in the Bastille was exiled to his estate of Fossé. He later made yearly visits to Paris. Apart from his collaboration with de Sacy, Thomas wrote some hagiographic works and left Mémoires (1697–1698 and again 1876–1879), which are highly praised by Ste Beuve as being a remarkable mirror of the life at Port Royal.