Saint Caesarius was a Physician, younger and only brother of Gregory of Nazianzus, born probably c. 330 at Arianzus, near Nazianzus; died at the end of 368 or the beginning of 369.
He received good training from his saintly mother Nonna and his father Gregory, Bishop of Nazianzus. He studied probably at Caesarea in Cappadocia, and then at the well-known schools of Alexandria. His favourite studies were geometry, astronomy, and especially medicine. In the last-named science, he surpassed all his fellow students. About 355, he came to Constantinople and had already acquired a great reputation for his medical skill, when his brother Gregory, homeward bound from Athens, appeared there about 358. Caesarius sacrificed a remunerative and honourable post and returned to his parents with Gregory.
The capital, however, soon proved to be too great an attraction for him; we find him occupying an exalted position as a physician at the court of Constantine and, much to the regret of his family, at that of Julian the Apostate. Julian failed in his efforts to win him over to Paganism. Caesarius, more appreciative of his faith than of imperial favour, ultimately left the court but returned to Constantinople after Julian’s death. Under Emperor Valens, he became quaestor of Bithynia.
His remarkable escape from the earthquake which shook Nicaea (11 October, 368) induced him to heed the insistent appeals of his brother and St. Basil, who urged him to leave the world. He was suddenly seized with a fatal illness, shortly after having received baptism, which he, like many others at the period, had deferred until late in life. He was unmarried and directed that all his goods should be distributed to the poor, an injunction which his servants abused in their own interests. His remains were interred at Nazianzus, where his brother pronounced the funeral oration in the presence of his parents.