A pope, a heretic, a saint, and a scientist walked into a classroom …

Pope Adrien VI, Jansen, St. Robert Bellarmine, Georges Lemaître — a pope, a famous heretic, a saint, and the “father of the Big Bang” — all passed through the prestigious Catholic University of Louvain (or Leuven). Pope Francis will visit this academic institution during his trip to Belgium, this September 27 and 28.

Let's take a look at these great men of history and the mark they left on the centuries-old university, which has been divided between the country's two linguistic communities — Flemish and Walloon — since 1968.

Founded in 1425, the University of Louvain acquired its noble status right from the start, as it was the training ground for the 218th pope: Adriaan Floriszoon Boeyens, who became pontiff Adrian VI after his election in 1522.

The Dutchman from Utrecht entered Louvain as a student at the age of 17 in 1476. He rose through the ranks, from professor to rector, and chancellor. It was within the walls of the university that he spent most of his life — almost 40 years — first as a student (he completed a doctorate in theology) and then as a teacher.

He then became Charles V's tutor in Ghent and Spain, where he was appointed Archbishop of Tortosa, before being created cardinal at the Emperor's request. He was unexpectedly elected pope in 1522, without even taking part in the conclave.

In Rome, he surprised everyone with his independence and his simple, pious life, drastically reducing the pomp of the papal court. Close to the poor and an uncompromising theologian, he recognized the wrongs of the Roman curia that had led to the Reformation, and attacked the abuses of the clergy, which earned him many enemies.

During his years in Louvain, he may have met Erasmus, who stayed there briefly twice in 1502 and 1514. The famous humanist philosopher of Dutch origin, who crisscrossed Europe, described Belgian academics as “less sophists than those in Paris.”

In any case, as a sign of his attachment to this place, Pope Adrian VI bequeathed his residence on rue du Mayeur to the city upon his death. A college named after him was opened there in 1524.

In the 16th century, other illustrious scholars crossed paths in Louvain, including Flemish cartographer Gerardus Mercator (1530-1532) and anatomist André Vesalius (1514-1564).

As one of Europe's oldest universities, Louvain was instrumental in the propagation of Latin. It was also a bastion of resistance to Protestantism, issuing the first censure against Martin Luther's writings as early as 1519.

The walls of the university were witness to the studies of the young Jesuit Robert Bellarmine (1542-1621), who spent time there as a pupil. The future cardinal and saint went on to teach for seven years at the nearby Jesuit theology faculty in Louvain, where he made a name for himself as a critic of the writings of Martin Luther and John Calvin, and a great defender of Rome.

In the context of the Counter-Reformation, however, Leuven was the “cradle” of Jansenism, the doctrine that the salvation of souls is predestined. Cornelius Jansen (1585-1638), the initiator of this theological trend, which was later deemed heretical by the Catholic Church, was a professor at the Belgian university.

The Bishop of Ypre, inspired by the thesis of one of his fellow professors, Baïus, wrote the Augustinus, which became a reference text in Leuven. In the 17th and 18th centuries, many of the university's teachers embraced “Augustinism”—a theology based on Augustine's themes of grace and predestination.

Another key figure at Louvain was astronomer and cosmologist Georges Lemaître (1894-1966), who forged his Big Bang theory here. The young scientist first wrote his thesis here in 1920. After further studies in Cambridge (England) and at the Harvard College Observatory in Cambridge (USA), he returned to Louvain as a professor in 1925, where he taught for almost 40 years.

It was at this university that the priest-scientist conceived the idea of the physical expansion of the universe, helping to discover the law of galaxy recession — known as the Hubble-Lemaître Law.

His dissertation on this work was published in 1927 in the Annals of the Scientific Society of Brussels, under the title “Un Univers homogène de masse constante et de rayon croissant rendant compte de la vitesse radiale des nébuleuses extragalactiques” (“A homogeneous Universe of constant mass and increasing radius accounting for the radial velocity of extragalactic nebulae”).

Lemaître was the recipient of the Prix Francqui (1934), Belgium's highest scientific distinction. He was also involved in the turbulent history of Louvain, vehemently opposing the split of the university between the Flemish and French languages that was to come about inevitably in 1968. He introduced the university's first electronic calculator (a Burroughs E 101) to Louvain, and his influence “shattered the immutable image we had of it until then,” acknowledges the official website of the university, which founded a chair in his honor.

The Catholic University of Louvain also boasts a Nobel Prize winner in medicine (1974): Christian de Duve (1917-2013), one of the fathers of cell biology. The Belgian doctor studied medicine and chemistry in Louvain before switching to the teaching profession to pursue a career in education and research.  

Louvain was also marked in the 20th century by another cardinal, the anthropologist Julien Ries (1920-2013), who founded the French-speaking university's Center for the History of Religions.