The origin of this little book, which is written from the point of view of Roman rather than of Christian history, may be explained in a few words. It was suggested by, and owes its existence to, an article by Professor Mommsen in the 'Historische Zeitschrift' of 1890, entitled, Der Religionsfrevel nach römischem Recht. The criticism of Professor Mayor and others on the insufficient and too hastily written essay on Pliny and the Christians in my edition of 'Pliny's Correspondence with Trajan' had led me to go into the subject with more thoroughness than I had hitherto given to it; and I was already convinced that on two points at least-viz. the importance of the Neronian persecution, and the connexion of Pliny's action in Bithynia with the government attitude towards collegia-I had followed quite erroneous views. It was Mommsen's article, however, which first seemed to give a clear and consistent account of the principles which underlay the action of the imperial government, not only towards the Christians, but towards foreign religions of all kinds, and I determined by means of the clue furnished by it to attempt an historical résumé of the relations between Christianity and the Roman government during the first two centuries.

I had been working at the literature of the subject and collecting materials for nearly a year and a half when Professor Ramsay's lectures on the Christian communities of Asia Minor were announced and delivered. As it was understood that these lectures were to be published, I put aside my own work, feeling that the ground was covered by his book, and intending, if possible, to make use of my materials in reviewing his lectures when they appeared. Subsequently, however, wishing to make somewhat more use than this would have allowed of my own work, such as it was, I altered my mind and reverted to my former intention, in the hope that there would be found sufficient difference in scope, method and arrangement to justify the existence of my little book side by side with, though at a respectful distance from, Professor Ramsay's.

To say that I have produced it quite independently of 'The Church in the Roman Empire' is impossible, and would be ungracious, because no one could read the book, as I have done with care, without being indebted to it in innumerable ways. Still it is to Mommsen's article that I am bound to acknowledge my chief indebtedness, and I am not conscious that my treatment of the subject is in any essential respect different from what it would have been if I had written it before Professor Ramsay's book appeared.