He soon grew so famous as a teacher, that even Jews, heathens, and heretics went to hear him; and many of them were so led on by him that they were converted to the Gospel. He travelled a great deal: some of his journeys were taken because he had been invited into foreign countries that he might teach the Gospel to people who were desirous of instruction in it, or that he might settle disputes about religion. And he was invited to go on a visit to the mother of the Emperor Alexander Severus, who was himself friendly to Christianity, although not a Christian. Origen, too, wrote a great number of books in explanation of the Bible, and on other religious subjects; and he worked for no less than eight-and-twenty years at a great book, called the _Hexapla_, which was meant to show how the Old Testament ought to be read in Hebrew and in Greek. But, although he was a very good, as well as a very learned man, Origen fell into some strange opinions, from wishing to clear away some of those difficulties which, as St. Paul says, made the Gospel seem "foolishness" to the heathen philosophers (1 _Cor._ i. 23). Besides this, Demetrius, the bishop of Alexandria, although he had been his friend, had some reasons for not wishing to ordain him to be one of the clergy; and when Origen had been ordained a presbyter (or priest) in the Holy Land, where he was on a visit, Demetrius was very angry. He said that no man ought to be ordained in any church but that of his own home; and he brought up stories about some rash things which Origen had done in his youth, and questions about the strange doctrines which he held. Origen, finding that he could not hope for peace at Alexandria, went back to his friend the bishop of Cæsarea, by whom he had been ordained, and he spent many years at Cæsarea, where he was more sought after as a teacher than ever. At one time he was driven into Cappadocia, by the persecution of a savage emperor named Maximin, who had murdered the gentle Alexander Severus; but he returned to Cæsarea, and lived there until another persecution began under the Emperor Decius.