Author: Mário Santiago de Carvalho
Part of: Coimbra Between Sciences and Education (coord. by Mário Santiago de Carvalho)
Peer-Reviewed: Yes
Published: February, 9th, 2021
DOI: 10.5281/zenodo.4522407

The latest version of this entry may be cited as follows: Carvalho, Mário Santiago de, “Delgado, João”, Encyclopedia, Mário Santiago de Carvalho, Simone Guidi (eds.), doi = “10.5281/zenodo.4522407”, URL = “”, latest revision: February, 9th, 2021.

Life and Works

Fr. João Delgado (1553-1612) stands among the first Portuguese Jesuits to contribute to mathematics and its development in the “prehistory” of the teaching of mathematics in Portugal within the Society of Jesus (Baldini 2004: 301). João Delgado was born in Lagos, Algarve (circa 1553), and died on September 30, 1612, in Coimbra. Despite the lack of information about his student years as a student, he studied (1576) mathematics and theology in Rome. In the Roman College, Delgado followed the lessons of the German mathematician and astronomer Christopher Clavius. João Delgado joined the Society of Jesus at the age of twenty-one (1574) and will remain in Rome for almost nine years. In Spring 1584, he turned back to Portugal with the task of going to Brazil as a missionary. Two years later, January 1586, he was still waiting to sail from his country to the land of Holy Cross (Terra de Santa Cruz), as the South-American territory was then called (Góis 1593: 317). It seems his health conditions were the reason why he never left Lisbon harbor. Consequently, Delgado was destined for a teaching career. First, he lectured a full course on mathematics at the College of Jesus (1586-1589), and several courses at the College of Santo-Antão in Lisbon (1590-1594, 1596-1597, 1605-1608). Perhaps it should remember now that Clavius had been a student in Coimbra (1556-1560), being an attentive reader of the mathematician Pedro Nunes’s works (Knobloch 2004), and a student of the philosopher Pedro da Fonseca. Thus one may assume that, while in Rome, teacher and student, viz. Clavius and Delgado shared conversations about the status of the Portuguese Province, and the standard of mathematics in Coimbra. Delgado’s knowledge of applied mathematics allowed him to take charge of the construction of the new College of Santo-Antão-o-Novo (1591), designed by the Italian architect, Giuseppe Valeriani. Delgado certainly met Valeriani in Rome but the Italian architect and painter had already been in Lisbon during the last quarter of the ’70s after entering the Society of Jesus (1574). João Delgado’s design skills as an architect became patent in the construction of the Novices buildings (Cotovia, Lisbon), and of the Coimbra College of Arts (1611), which had been handed over to the Society of Jesus in 1555. João Delgado did not publish any oeuvre and his lessons and mathematical contributions can only be accessed through his students’ notes and the manuscripts he left (Leitão 2004: 747-8, Silva & Ferreira 2008: 103-08). However, based on Rodrigues (1931b), Carvalho (2001) recalls that Delgado’s complete course on mathematics, written in the Portuguese language, did exist and that his superiors welcomed its translation into Latin. Rodrigues explained that the book did not reach the press, due to the author’s death. Delgado’s teaching years in Lisbon were remarkable especially due to the contribution he gave to the “Aula de Esfera” (“Courses on the “Sphere”, inaugurated 1590) at Santo-Antão College; as a matter of fact, and as far as it is known, he was the first teacher of mathematics there (Leitão 2007: 46). The attribution to Delgado of the B.G.U.C. Manuscript # 1184, Explanationes in sphaeram Ioannis de Sacrobosco… anno salutis 1587, is based on a coincidence between the date mentioned in the manuscript and the year Delgado was almost beginning his lessons on mathematics in Coimbra (1586-1589). The manuscript and its content testify that the Jesuits offered private lessons in mathematics, at the College of Jesus, as an alternative to those given by the University of Coimbra (Gomes 2012: 237). It is perhaps odd but after Nune’s teaching period at the University (1554-1562), his chair remained vacant until 1592, when it was given to André do Avelar (Martins 2020: 316, 319). Baldini’s above mentioned historical division roots in the historian thesis according to which before 1590 no public teaching of mathematics given by the Jesuits existed. This is correct, but shadows other aspects of mathematics teaching in Coimbra. Provided it is his, Delgado’s manuscript of Coimbra has no connections with the fact that De Sphaera was related with the formal teaching of the De Caelo, i.e. “before reading Aristotle’s De coelo, in the second or third class [of philosophy].” (Baldini 2004: 301). Indeed, such were the rules given by the University to the College of Arts in 1559. Moreover, Baldini (1998), as well as Martins (2020), have called the attention to extant manuscripts having this mixture-kind of approach, e.g. João Gomes de Braga’s or Luís de Cerqueira’s. It is also true that while designing the Coimbra Jesuit Course, in its very beginning, Fonseca charged Cipriano Suárez to dwell on Aristotelian mathematics, meaning De Caelo and Meteororum, as well as on chapter four of Sacrobosco’s De Sphaera (Carvalho 2010: 16). However, the Explanationes in sphaeram Ioannis de Sacrobosco… anno salutis 1587 do not fit into such a scheme. Among other reasons, because they were not taught to become part of a philosophical course like those lectured at the College of Arts.  Several indications allow one to sustain that independent courses on the Sphere were given by the Jesuits and aiming at Sacrobosco’s book in its entirety. For instance, one manuscript from the Library of the Évora Municipality (BPE), CXXVI/2-4, registers the lessons by Vasco Mergulhão Baptista, dated 1585, and by António de Castelo Branco, dated 1588. All together, they cover five books. One is not claiming that high levels of mathematics could be found in all those manuscripts, but it is wrong to think that mathematics could only be part of the Aristotelian course, thus having a subsidiary feature. Golvers’s more recent research indicates that the practice of private lessons in Coimbra was a fact (see e.g. Golvers 2018), and one may believe that more discoveries are still to come. As indicated below, in the bibliography section, João Delgado taught a course on astronomy, in 1605/06, and on practical astrology, in the next year (1606/07). His life and scientific contributions still await systematic research. Meanwhile, we may stick to Leitão’s list of Delgado’s mathematical main topics, meaning, cosmography (at an introductory level), astronomy (being more than a mere introduction and paying close attention to theoretical astronomy), gnomonic (at a theoretical advanced level), and astrology (see Carolino 2003: 104-5). Historian Leitão (2007: 46-47) concludes that “… without being a creative mathematician, his [Delgado’s] competence is beyond doubts” but two aspects of his contribution were already recognized. First, Delgado’s lessons about mathematics distance from the similar theses of philosophers such as Piccolomini, in Padua, or Perera, in Rome (Lamanna 2014: 73-6), as well as Fonseca, in Coimbra (Baldini 2004: 312). Second, as far as the “quaestio de certitudine mathematicarum” is concerned, Delgado was one of the first Jesuit mathematicians to argue that “mathematics fit all the main features of Aristotelian science, and therefore it should be considered as a true science (…) within a strict Aristotelian framework” (Carolino 2006).


Delgado’s works

  • Explanationes in sphaeram Ioannis de Sacrobosco… anno salutis 1587, Biblioteca Geral da Universidade de Coimbra ms. 1184.
  • Tratado breve dos relógios dados em S.Ant. Ano de 1596.
  • Teóricas dos planetas do padre João Delgado da Companhia de Jesus (1598).
  • Esfera do Mundo, BACL ms. 491 V, and Biblioteca Publica Municipal do Porto, ms. 664 (1605-1606) = [Lessons in Cosmography, and in the Theory of Planets].
  • Astrologia Prática ou Iudiciária, Biblioteca Nacional de Lisboa Cod. 2130 [ms. F.G. 664], BNL ms. Cod. 6353, and Biblioteca Nacional de Madrid ms. 8931.

Secondary references

  • Baldini (1998), Ugo. “As Assistências ibéricas da Companhia de Jesus e a actividade científica nas missões asiáticas (1578–1640). Alguns aspectos culturais e institucionais”, Revista Portuguesa de Filosofia 54 (2): 195-246.
  • Baldini (2004), Ugo. “The teaching of Mathematics in the Jesuit Colleges of Portugal, from 1640 to Pombal”, in Saraiva & Leitão (2004), 293-465.
  • Carolino (2003), Luís Miguel. Ciência, Astrologia e Sociedade. A Teoria da Influência Celeste em Portugal (1593-1755), Lisbon: Fundação Calouste Gulbenkian.
  • Carolino (2006), Luís Miguel. “João Delgado S.J. e a ‘Quaestio de certitudine mathematicarum’ em inícios do século XVII”, Revista Brasileira de História da Matemática 6/11: 17-49.
  • Carvalho (2001), J. Vaz de. “Delgado, João”, in Diccionario Histórico de la Compañía de Jesús. Biográfico-Temático, directores Charles E. O’Neill & Joaquín Mª Domínguez, Roma-Madrid: Institutum Historicum, S.I. – Universidad Pontifícia Comillas.
  • Carvalho (2010), Mário Santiago de. Psicologia e Ética no Curso Jesuíta Conimbricense, Lisbon: Edições Colibri.
  • Catalogs, from 1586 to 1611, at Archivum RomanumI., Lus. 39, and 44.
  • Crowther (2020), Katheleen M. “Sacrobsco ‘Sphaera’ in Spain and Portugal”, in Valleriani (2020), 161-184.
  • Góis (1593), Manuel de. Commentarii Colegii Conimbricensis S. J. In Quatuor libros de Coelo Aristotelis Stagiritae, Lisbon: S. Lopes.
  • Golvers (2018), Noël. “A Ray of Light on Private Mathematical Culture in Coimbra in the Mid.17th century: Francisco Pereira de la Cerda (+1656)”, Revista Filosófica de Coimbra 27: 65-76.
  • Gomes (s.d.), João Pereira. “Delgado, João”, in Enciclopédia Luso-Brasileira de Cultura, Lisbon: vol. 6,  c. 937 [now in Gomes 2012: 121].
  • Gomes (2012), João Pereira. Jesuítas, Ciência e Cultura no Portugal Moderno. Obra selecta do Pe. João Pereira Gomes, org. por H. Leitão e J. E. Franco, Lisboa: Esfera do Caos.
  • Knobloch (2004), Eberhard. “Nunes and Clavius”, in Saraiva & Leitão (2004), 163-194.
  • Lamanna (2014), Marco. “Mathematics, Abstraction and Ontology: Benet Perera and the Impossibility of a Neutral Science of Reality”, Annuario di storia della metafisica 14: 69-89.
  • Leitão (2004), Henrique. “Appendix C: Scientific Manuscripts from the S. Antão College”, in Saraiva & Leitão (2004), 745-758.
  • Leitão (2007), Henrique. A Ciência na “Aula da Esfera” no Colégio de Santo Antão 1590-1759, Lisbon: Comissariado Geral das Comemorações do V Centenário do Nascimento de São Francisco Xavier.
  • Martins (2020), R. de Andrade. “André do Avelar and the teaching of Sacrobosco’s Sphaera at the University of Coimbra”, in Valleriani (2020), 313-358.
  • Rodrigues (1931a), Francisco. História da Companhia de Jesus na Assistência de Portugal, tomo 1 (A Fundação da Província Portuguesa), vol. 1: Origens, Formação, Ministérios, Porto: Apostolado da Imprensa.
  • Rodrigues (1931b), Francisco. História da Companhia de Jesus na Assistência de Portugal, tomo 1 (A Fundação da Província Portuguesa), vol. 2: Tribulação, Colégios, Missões, Porto: Apostolado da Imprensa.
  • Saraiva & Leitão (2004), Luís, and Henrique (eds.). The Practice of Mathematics in Portugal. Papers from the International Meeting organized bt the Portuguese Mathematical Society (Papers from the International Meeting held at Óbidos, 16-18 November 2000), Coimbra; Imprensa da Universidade de Coimbra.
  • Silva & Ferreira (2008), Ana Cristina, and Teresa Duarte. Catálogo, in Henrique Leitão (ed.), Sphaera Mundi: A ciência na Aula da Esfera. Manuscritos científicos do Colégio de Santo Antão nas colecções da BNP, Lisbon: Biblioteca Nacional de Portugal, 99-247.
  • Valleriani (2020), Matteo (ed.). ‘De Sphaera’ of Sacrbosco in the Early Modern Period. The Authors of the Commentaries, Cham: Springer Open.