When Cardinal Jorge Mario Bergoglio took the name Francis on being elected the 267th Pope of the Catholic Church on Wednesday, the Jesuit from Buenos Aires was only following a papal tradition that began in AD 533 with Mercurius who chose the name John II.

Mercurius changed his name as he felt that his baptismal name was that of a Roman god and it would not augur well for a pope to be known by that name. Since then, all popes except Adrian 1V (1522 to 1523) and Marcellus 11 (1555) have changed their baptismal names and took the names of their predecessors, mentors or saints during their pontificate.

It’s decision tied up in history and tradition, and it has more than a little symbolic value. In papal tradition, newly elected pontiffs choose a name to identify themselves during their reigns. A papal moniker offers an early indicator of what his papacy might be like and it will reflect his own personal spirituality.

That Pope Francis has chosen a new name may signal that he wants to lead the church into a new chapter. Many see it as a tribute to St. Francis of Assisi, the 13th century saint who lived in poverty and heard a voice to “rebuild the Church.” Pope Francis being a Jesuit, the name could also be a reference to Francis Xavier, a co-founder of the Jesuits in the 16th century.

John was the most common name used by popes over the years. As many as 23 popes have taken the name. The names Gregory and Benedict have been chosen by 16 popes each. Fourteen popes have chosen the name Clement, Leo (13), Innocent (12), Pius (12), Stephen (9), Urban (8), Alexander (7), Adrian (6), Paul (6), and Martin (5), Nicholas (5) and Celestine (5). Four popes each have been known by the names Anastasius, Eugene, Sergius, and Honoriu.

The last pope to inaugurate a name was John Paul I, in 1978, who did so in honour of his two immediate predecessors, John XXIII and Paul V1.

He died 33 days later to be succeeded by John Paul II, a name taken in his honour by the Pole Karol Wojtyla.

Saint Peter the Apostle was the first pope and no pope after him had chosen the name Peter. They include even popes John X1V and Sergius 1V who had their baptismal names as Peter.

Telesphorus, Eleutherius, Zephyrinus, Eutychian, Miltiades, Hormisdas, Zosimus, Symmachus, Simplicius, and Vigilius are some most unique papal names.

Interestingly, it was the first pope Peter who remains the longest serving pope. According to the Catholic Encyclopaedia, he reigned for 35 years (Ad 32 to 67). But after that, it was Pope Pius IX (1846 to 1878) who was the longest serving pope, 31 years and seven months. Pope John Paul 11, who passed away in 2005, was the third longest serving pope: 26 years and 5 months.