AVENDAÑO, Diego de. - Jesuit theologian and canonist, b. at Segovia (Spain) in 1594, d. at Lima (Peru) on 31 Aug. 1688. After studying philosophy at Seville, he went to Peru in 1609 with the famous jurist Solórzano Pereira and entered the Society of Jesus at Lima in 1612. Upon completing his theological studies, he taught rhetoric and humanities at Lima, philosophy at Cuzco, and theology at the University of Chuquisaca (now Sucre) and at the Major College of St Paul in Lima. Later engaged in administration, he served as rector at Chuquisaca, vice-rector at Cuzco, rector of the Major College of Lima, vice-provincial (1661) and provincial (1663) of the Jesuits in Peru, and rector of two houses in Lima until 1672. He was then able to devote himself to the preparation of his works until old age (1685) prevented him.
He wrote: *Epithalamium Christi et Sacrae Sponsae, seu Explanatio Psalmi XLIV*, Lyon 1663; *Amphitheatrum misericordiae seu Expositio Psalmi LXXXVIII*, Lyon 1666; *Problematia theologica*, 2 vols., Antwerp 1668. But his principal work is the *Thesaurus Indicus, seu Generalis Instructor pro Regimine Conscientiae in iis quae ad Indias spectant*, 6 vols., Antwerp 1668–86 (vols. III–VI are “actuaria”; vol. VI is sometimes issued separately under the title *Cursus communatus*). The work lacks a little in organic plan and sometimes in precision, but its merit lies in having applied the general principles of Catholic morality and canon law to the particular cases of the West Indies; it has been described as “an encyclopedia for missionary pastoral care and for missionary and colonial law” (Streit). The author left other manuscript works, such as the *Litterae annuae* of the Jesuit Province of Peru for the years 1662–65, necrological records of several Jesuits, and a treatise *Mysterium Fidei*.