Christianity had not been persecuted for half a century, and had made great progress. The cult of the old gods was palpably insincere, and half-a-dozen Asiatic creeds were steadily supplanting it. On the streets of Nicomedia, as on the streets of Rome or any other large city, one might meet any day the white-robed shaven priests of Isis, the painted and effeminate ministers of Cybele, the Persian representatives of the popular cult of Mithra, and--until they were expelled by Diocletian--the black-garbed clergy of the Manichæans and the Christians. The Christians were now advancing. There had been some slight and irregular repression of them from time to time since the days of Nero, but more than forty years of toleration, and the knowledge that their adherents were now occupying high places in the camp and the court, and that even the wives of the Emperor and the Cæsar favoured them, gave them strong confidence. One of their churches occupied a central and commanding position in Nicomedia. Four influential officers of the court attended it, and it seems that Valeria and Prisca were, if not Christians, openly disposed to the new religion. All we know in that regard is that they were “compelled” to sacrifice when the persecution began. Persecution on account of religion, as such, was not natural to the cosmopolitan builders of the Pantheon, and Diocletian was a broad-minded statesman, so that the origin of the persecution is not so clear as it was once held to be. The literary remains which we have to use have to be handled with caution. The “Historia Augusta” has ended with Carinus, and we shall greatly miss its minute and gossipy descriptions. Zosimus, a pagan writing in a Christian age, has an appearance of sullen reticence at times and a perceptible bias. Aurelius Victor and Eutropius are scanty, and the immediate Christian writers are used very cautiously by modern historians. Bishop Eusebius says frankly, in his “Life of Constantine,” that he will write only what tends to edify, and the little work “On the Deaths of the Persecutors” is obviously imaginative in many pages and inaccurate in others. Experts still differ as to whether it comes from the pen of the brilliant Christian rhetorician Lactantius, but all warn us to take account of its strong feeling. Our authorities, in a word, now belong to two antagonistic and bitterly hostile creeds, and, as all subsequent historians favour one side or the other, we have to proceed with caution. I have endeavoured, in the remaining chapters, to make my way between them with more than ordinary care and independence.