In the early development of their spiritual and theological roots, the Sisters of Mercy are indebted to many Irish diocesan priests and to many religious orders active in Dublin and the surrounding area during the early nineteenth century, especially to those most supportive of Catherine McAuley and the first Sisters of Mercy prior to and following the founding of the Institute of Mercy in Baggot Street in 1831. Among the religious orders, the Carmelite Fathers on Clarendon Street, the Presentation Sisters on George’s Hill, the Dominican Fathers at Carlow College, the Irish Sisters of Charity (in the person of their founder, Mary Aikenhead), the Poor Clares, and the Irish Christian Brothers come immediately to mind. The theological debt of Catherine McAuley (1778–1841) and the Sisters of Mercy to the Society of Jesus, however, is fundamental and quite specific. The subsequent historical affiliations of the Sisters of Mercy with members of the Society of Jesus and the frequent consultations which many congregations of Sisters of Mercy have had, and continue to have, with various Jesuit advisers and spiritual directors have their earliest exemplar in the remarkably close association of Catherine McAuley with the classical religious writings of the well-known sixteenth-century Spanish Jesuit theologian, Alonso Rodriguez (1526–1616). This intellectual relationship is suggested by much in Catherine’s thought and writing, but, for the purpose of this article, most notably in the remarkable parallels that exist between Catherine’s only long essay and Rodriguez’s early seventeenth-century essay on the same general theme.