"Under the starry coat of astronomy, our saint religion finds an easy way forward"
It wasn't on paper only that this lifelong project was intended to be "complete". Although the so-called "Western" astronomy, from Babylon and Egypt to Huygens and Cassini, through Greece, Rome and Alexandria, was central, it was only a part of a truly universal project. It was necessary to establish a real dialog between the European astronomical tradition and the other traditions which were almost completely unknown until that time. Such was the case of the Chinese tradition, for instance. But, fortunately, Jesuit missionaries had been working on it for almost a century.
After arriving in Macao in 1582, Matteo Ricci gained a considerable prestige by predicting the solar eclipse of 1596. He was called to the court of Beijing a few years later to contibute, among other things, to the reform of the calendar. This task, in a Confucean society, was of the highest importance, since the society is ruled by rites aimed to keep harmony between Heaven, Earth and Humankind, down to the smallest detail. The course of the stars is a major issue, and the Emperor is the "Son of Heaven". It makes it possible to devote auspicious and harmful days to every human activity.
Benefiting from the progress of the European sciences, the missionaries ensured their domination over the Chinese tradition as well as over the Islamic one, which had been active in Beijing since the Mongolian Yuan dynasty of the XIIIth-XIVth centuries. Once again, the Jesuits managed to predict rather precisely the time and magnitude of the solar eclipse of 21st June 1629, and the emperor Chongzhen entrusted them with the reform of the calendar. 1 The responsibility fell upon the German Johann Schall von Bell (arrived in Beijing in 1630) together with the Italian Giacomo Rho and the Chinese Catholic Xu Guangqi.
Father Johannes-Adam Schall von Bell, main architect of the calendar's reform the Qing passed in 1645
The reform is completed around 1640. After overthrowing the Ming dynasty in 1644, the Manchurian Qing dynasty first renewed the confidence granted to the Jesuits. Schall even became the "Head of the Mathematical Board", a highly political function. The new calendar was officially proclaimed, and European calculation methods gained a foothold.
But the Jesuits' social position, which relied on the predictive capacities of the modern sciences, remained precarious. They had to cope with the Mandarins' envy and rejection of the Christian proselytism. 1 Because of a miscalculation of Emperor Shunzhi's son's funeral, Schall and Verbiest were sentenced to death and imprisoned.
Pather Ferdinand Verbiest who, succeeding Schall, establishes the observatory which can still be seen in Beijing
New "miracle" : an earthquake happened on 16th April 1665. It was understood as an auspicious sign in their favour and they were released from jail. Schall died from mistreatment, but Verbiest's position was enforced in the entourage of the new emperor, Kangxi, who acceded to the throne in 1666. A phrase of Father Verbiest sums up the Jesuits' tactical use of astronomy : "Under the starry coat of astronomy, our saint religion finds an easy way forward." 1
In this letter sent from Siam on Mai 6, 1686, Fontaney sends Cassini his eclipses logs, and asks him for instruments for the observatory of Beijing.
To increase the Jesuit population in Beijing, Verbiest applied to the Society of Jesus, but also to France, and asked for new scientists. Colbert answered by sending a group of six missionaries, the "King's Mathematicians".
Their leader, Father Jean de Fontaney, was on very good terms with Jean-Dominique Cassini, and sent him many astronomical records from Beijing.
In line with these relationships, Delisle corresponded with Father Antoine Gaubil, settled in Beijing in 1723 to take over from the Mathematicians. Gaubil consigned many of his "papers on Chinese astronomy" to him.
Gaubil was a first-classe source for Delisle : he is considered by Paul Demiéville as "the greatest European Sinologist in the 18th century, the best thinker among the French Jesuits who then established the first Western school of erudite studies about China, in China itself." 4
1 A superiority which was in no way an absolute one, as the astrophysicist Jean-Marc Bonnet-Bidaud points out : "The competition is tight. With an error of one minute only, the Chinese bureau gives the best prediction of the eclipse's maximum's hour, whereas the Jesuits are ten minutes early, and the Islamic bureau makes a mistake of more than one hour. However, the Jesuits are the best at predicting the eclipse's magnitude. They make an estimation of the fraction of the Sun occulted by the Moon of 16%, instead of 20% in reality, whereas the Chinese bureau gives 32%." (4000 ans d'astronomie chinoise. Les officiers célestes, Paris : Belin / Humensis, 2017, p. 154.)
2 The Chinese astronomer Yang Guangxian is a spokesperson for the opponents to Schall, in a "Complaint Requesting Punishment for the Evil Religion". Ibid., p. 157.
3 "Imo ipsa sacra religio stelliferam astronomiae pallam passim induta", words of 1678 quoted by the historian Isabelle Landry-Deron. "Les Mathématiciens envoyés en Chine par Louis XIV en 1685 ", Archive for History of Exact Sciences, 55, Berlin : Springer Verlag, 2001, p. 423-463.
4 Foreword by Paul Demiéville to the Correspondance de Pékin by Father Gaubil, published by Renée Simon in 1970 (Genève : Droz). The discussions with Delisle spanned over more than two decades (1732 to 1758).