ARNAULD, the surname of a family of prominent French lawyers, chiefly remembered in connection with the Jansenist troubles of the I7th century. At their head was ANTOINE ARNAULD (156o-1619), a leader of the Paris bar; in this capacity he de livered a famous philippic against the Jesuits in 1594, accusing them of gross disloyalty to the newly converted Henry IV. This speech was afterwards known as the original sin of the Arnaulds.
Of his 20 children several grew up to fight the Jesuits on more important matters. Five gave themselves up wholly to the Church.