An uncompromising, intellectually rigorous order of priests and brothers within the Roman Catholic Church: the Society of Jesus. It was founded in the sixteenth century by Ignatius "Loyola" (1491-1566), a Spanish knight from a noble Basque family. The Society of Jesus, or "S.J.," enjoys a reputation of being the most intellectually rigorous of the orders, a reputation based on its members’ work in education and intellectual research.