Baring-Gould’s sources: Roman Martyrology. Greek Menæa on March 9th. Authority:—His life, written by his brother, S. Gregory Nazianzen.

S. Cæsarius was given by his parents an excellent education, and, being a man of great natural parts, he soon distinguished himself for his accomplishments in all the known sciences. He became one of the first physicians of his day, and was urged by the Emperor Constantius to reside in the imperial city, but declined to do so. Julian the Apostate [Roman emperor 361–363 who tried to restore paganism] nominated him his first physician, and loaded him with marks of favour, without, however, being able to shake his Christian constancy. Jovian, who succeeded Julian, also honoured him, and finding that, moved by the remonstrances of his father and brother, Cæsarius had thrown up his appointment at the court of the Apostate, he recalled him. Valens created him keeper of the privy purse, and treasurer of Bithynia. A narrow escape in an earthquake at Nicæa, in 368, when almost all the chief men of that city were killed, moved him to renounce the world. He died shortly after, and was buried with great solemnity, his parents assisting at the funeral with lighted tapers in their hands, and his brother, S. Gregory, Bishop of Nazianzus, preaching his funeral oration.