the ‘Decline and Fall’ were employed to discredit Christianity rather than to try to discover amid the fierce wranglings of theologians over insoluble problems what was their signification for the history of the time of which he was treating and in the development of the human mind. He began with a period in which the emperor is worshipped as Divinity and traced the establishment of Christianity as a national faith among Pagan subjects until in a diversified form it became accepted by all; but he did this without affording us any help to see how the human mind could accept the first position or what were the movements of thought which led to the evolution of the questions which agitated men’s minds in the later period. The century in which he and his contemporaries lived was for them one of hostility to Christianity rather than of investigation, the period of Voltaire, who could only see in Byzantine history ‘a worthless repertory of declamation and miracles, disgraceful to the human mind’ rather than of the Continental and English writers of the modern historical school. Happily, in the twentieth century those who look upon Christianity with an independence as complete as that of Gibbon recognise that insight can only be obtained by sympathetic investigation, that for the right understanding of history it is essential to put oneself in the place of men who have attached importance to a religious controversy, to consider their environment and examine their conduct and motives from their point of view, if we would comprehend either the causes which have led such controversy to be regarded as important or the conduct of the controversialists themselves. The absence in Gibbon of any sympathetic attempt to understand the controversies which play so large a part in his great drama of human history renders him as unsatisfactory a guide in regard to them as a writer of English history during the period of Charles the First would be who should merely treat with contempt the half religious, half political questions which divided Englishmen. While the objection I have suggested to Gibbon’s attitude would apply generally to his treatment of religious questions, I have only to deal with it in reference to the period of which I am treating. When writing of this period Gibbon did not realise that the religious question was nearly always a political one, and that union with Rome meant subjection to Rome. But unless it be realised how completely the citizens of Constantinople and the other great cities of the empire were engrossed with semi-religious and semi-political questions, no true conception of the life of the empire can be formed; for these questions were of interest not merely to Churchmen but to all. Among the documents brought to light during the last fifty or sixty years which have contributed to our better knowledge of the siege the most important are the ‘Diary’ of Nicolo Barbaro and the ‘Life of Mahomet’ by Critobulus.