John joined that relatively new and controversial religious order while he was a young man. The order sent him to Paris for his studies and eventually he obtained a teaching position there.
Several years later, serious accusations were lodged against his religious order and he was forced to stop teaching.
Shortly after that, at the age of 36, he was elected head of the order.
John defended the order against its detractors, dealt with serious divisions within the order, and made important changes within it.
After about ten years, the Pope vindicated John’s order and formally condemned its greatest critic.
The Pope would eventually force John to become a Bishop and then a Cardinal.
John became widely known for his theological wisdom and personal holiness (there were many stories of miracles). He went on to have a great influence on the Universal Church: advising Popes and acting as the guiding force of an Ecumenical Council.
Suddenly, while the Council was still in session, John died, still in his early 50's. He may have been poisoned by his enemies, but they could not conquer him: his order - the Franciscans - would continue and his theological writings would be venerated as among the best of all time.
But John's name would not be remembered, for he had stopped being known by his baptismal name.
There were many different stories about where he got the new name. One story says that when John was a little boy, his parents had brought him to the great St. Francis, not long before his death, and that St. Francis himself was the origin of John’s new name: Bonaventure.
Bonaventure was recognized as a saint with little delay. In due course, he was listed as a "Doctor of the Church."
His memory is celebrated on this day - the anniversary of his death in 1274.
(Adapted from an earlier post)