He studied or taught at Jesuit colleges across Catholic Europe, including Bordeaux, Douai, Graz, Mainz, Leuven, and Salamanca.
He was the friend of the Flemish humanist Justus Lipsius, a relative of Michel de Montaigne, and an enemy of the Protestant scholar Joseph Scaliger.
Martin Delrio was born in Antwerp on 17 May 1551, Whit Sunday, to the Spanish merchant Antonio del Río (d. 17 February 1586) and his wife Eleonora López de Villanova (d. 21 April 1602).
[2] There he studied under the humanist Cornelius Valerius and met a number of other young promising scholars, including Andreas Schott, Willem Canter, and Justus Lipsius.
Delrio's first publication, an edition of the late Roman grammarian Gaius Iulius Solinus, was based on a manuscript borrowed from Lipsius and included suggested emendations by his tutor Valerius.
[4] He also spent some time in Douai where he refused to share a bed with an unnamed famous man (cited by his 1609 Jesuit hagiography as proof of his chastity).
On 7 September 1561, at the age of 10, Martin Delrio made his official entry, swearing an oath in which he promised to protect widows and orphans.
[8] The Delrio family also paid host to a number of prominent figures on visits to Antwerp, including Antoine Perrenot de Granvelle and Anne of Austria, Queen of Spain, Philip II's fourth wife.
With the onset of the Dutch Revolt members of the family found employment with the Council of Troubles, the repressive institution set up by the new governor-general Fernando Álvarez de Toledo, 3rd Duke of Alba.
Credentials or qualifications were irrelevant; with the exception of one loyalist member who fled to Paris, none of the existing councillors had decided to follow Don John.
[10] Another victim seems to have been the memoirs which Delrio composed in honour of his patron Don John of Austria and in ostensible imitation of Caesar's De Bello Gallico.
[11] On 27 December 1579 Martin Delrio wrote from Maastricht to the Jesuit General Everard Mercurian seeking to join the Society of Jesus.
Delrio professed a sincere conversion to the religious life, but with his career side-lined and his family connections either dead or in exile he might also have had little choice.
At the same time his close personal involvement as well as his family's role in the Dutch Revolt also meant that Martin could only ever see the conflict in religious terms.
Whether he met Bordeaux's mayor, the famous essayist Michel de Montaigne, while there, is unclear, but the two men were second cousins on their maternal side.
[13] It is at this time that Delrio began work on his first publication since his entry in the Society, a substantially revised and expanded version of his edition of Senecan Tragedy.
During these years he also gave a number of sermons in honour of the Virgin Mary, which he collected and published under the title Florida Mariana (Marian Blossoms, 1598).
Martin Delrio's Magical Investigations (Latin: Disquisitiones Magicae or Disquisitionum Magicarum Libri Sex) first appeared in three volumes in Leuven in 1599 and 1600, printed by Gerard Rivius.
Wolfgang Behringer argued that Delrio drew on his experience as a young magistrate, which made him in effect "a colleague of Nicolas Remy".
(Delrio's student Heribert Rosweyde would play an important role in the emergence of the Acta Sanctorum, a Catholic encyclopedia of saints lives.)