Today we honor a saint, the saint from whom San Diego gets its name. Diego is his Spanish name. In English he is known as Didicus. 
He was born to a poor family around 1400 in Andalusia, in the diocese of Seville. The town of his birth was San Nicolás de Puerto. He wanted to live a life of solitude and penance, and initially did so as a hermit at the Church of St. Nicholas under the guidance of a holy priest. He supported himself by crafts. Like the desert fathers a thousand years before him, he wove wicker baskets of local materials. He also made household utensils like spoons, bowls, and salt cellars. He didn't want any money in exchange, just the simple necessities of life, like cloth to make and repair his simple clothes.
He began to acquire a reputation for holiness, and people would even come from surrounding towns to see him. Thus he lost the solitude that he loved. So he went to the friary of Arezapi, not far from Cordoba, where he was received into the order, into the Franciscan order, as a religious brother and made his novitiate. Now he would have a community to protect his recollection. 
He was an exemplary friar with a love of prayer and penance. He was compassionate toward the poor and would share his food with them. Miracles began to happen around him. The bread that he gave to the poor would be multiplied in his hands. 
Once he went with another friar to the house of a benefactor in Seville. Nearby there was a woman who worked as a baker. She had a seven year old son who had done something for which he knew he would get in trouble, so he hid. And he decided to hide in the oven, which was cool at the time. And he stayed there so long that he fell asleep. When it was time to make the bread, the woman, still not knowing where her son was, loaded the oven with wood and kindled the fire to heat the oven. This woke up the boy who called out in the midst of the flames. The woman couldn't save him and ran through the streets screaming and panicked, looking for someone who could help her. She ran into St. Didicus and explained what was happening. So he told her to go to pray for her son at the altar of the Immaculate Virgin and not worry. And he went to the oven and called the boy who climbed out over the hot coals without being burned. 
Like many saints, Didicus was very devoted to Our Lady. He praised her frequently to get others to love her as much as he did. On various occasions, he healed people with the oil from the lamp that burned in front of one or another image of her. 
Back in 1405, the island of Fuerteventura in the Canaries had been conquered, just when Didicus was a small boy. Two Franciscans accompanied the expedition and they began the evangelization of the island. In 1441, St. Didicus was sent as a missionary to the natives. This wasn't something he was looking for, but he accepted this undesired obedience, consoling himself with the thought of extending the kingdom of God and perhaps obtaining martyrdom. 
In 1446, the first friary was built and St. Didicus was unanimously elected guardian. His reputation for holiness and prudence led them to make an exception to the rule that lay brothers cannot be superiors, because the work of the Franciscans is primarily priestly work, so ordinarily a layman shouldn't be telling priests what to do. As the head of the missionaries, he tried to protect the natives from the conquistadores. Since he made it difficult for them to do what they wanted, they made it difficult for him to do what he wanted. And the conflict got to the point that in 1449, he asked to return to Spain. But before that, he made an attempt to evangelize another of the islands in the Canaries, the Gran Canaria. 
This is the next largest island in the archipelago, 60 miles to the west. It was still under native control and therefore full of pagans who had no one to preach Christ to them. St. Didicus wanted to go evangelize them and save their souls or become a martyr in the attempt. But when he tried to get there, a great storm arose, forcing his ship to return to Puerto Ventura. So he understood that what he had planned was not God's will. 
In 1449, his request to return to the mainland was accepted. The next year, 1450, was a jubilee year and the canonization of Bernardino Siena had been announced as well. St. John of Capistrano was at that time the vicar general of the observant Franciscans, that is the head of a reform within what was then the sole order of Franciscan friars.
He invited all the observant Franciscans, all the members of his reform, who could, to come. And almost 4,000 did come to Rome, including St. Didicus. Many well-known Franciscans were among the pilgrims, including St. James of the Marches, another pillar of the observance. It was a joy for St. Didicus not only to meet so many holy and well-known friars, to see the Pope. He could also visit the tombs of the Apostles, venerate the relics of many saints, and of course attend the canonization of St. Bernardino of Siena. 
Unfortunately, many of the Franciscan pilgrims were worn out by the long trip, and with the the cold climate they fell ill, so that a large infirmary had to be set up in the friary of Araceli. This friary was by the Roman Forum. It was almost entirely demolished in 1886 after the suppression of religious orders. 
Among the sick back in 1450 was St. Didicus's traveling companion, Fr. Alfonso de Castro. When the Guardian saw with what charity St. Didicus served his companion, he decided to put him in charge of the whole infirmary. So he wound up taking care of the sick there for three months, and he healed many with the water from the friary well, or with oil from the lamp that burned in front of the image of the Virgin. 
When he got back to Spain, he was permitted to retire to the solitary friary of Our Lady of Salceda, the first friary of the observance in Spain. And there he dedicated himself to prayer and contemplation. He was later transferred to the friary at Alcalá de Henares, where he spent his last years with such virtue and working so many miracles that his name became known throughout Spain as Didicus of Alcalá. 
He died on November 12, 1463. His last words were from the Passion Liturgy, O sweet wood, O sweet nails that had the fortune to bear the King and Lord of Heaven. There was no rigor mortis in his body. And later when his body was exhumed, because the miracles kept occurring, he was found incorrupt and transferred to a church. 
Almost 100 years after his death in 1562, Carlos, the son of King Philip II of Spain, fell down a staircase and hit his head. The teenager was close to death and various remedies were tried. Among these, the body of St. Didicus was brought to his bedside. Carlos recovered and the King credited Didicus with saving his son and eventually convinced Pope Sixtus V to canonize him in 1588. 
Since he's the first non-martyr Franciscan religious brother to be canonized, he's the patron of Franciscan religious brothers. He became one of the most popular saints among Spanish speakers. And so in 1602, the Spanish explorer who was mapping the California coast had a flagship named San Diego, and he gave that same name to the region where the city of San Diego now stands. Thus the Lord exalts the humble, making their names famous throughout the earth. Praised be Jesus and Mary.