Commemorations which mark the definition of a dogma, or which originated in the special emphasis given at some particular epoch to certain aspects of popular belief and sentiment, have all appeared at times well within the ken of the historical student. Thus, ‘Orthodoxy Sunday’ (the first Sunday in Lent) in the Kalendar of the Greek Church is but little concerned with the controversies on the right faith which occupied the great Councils of the fourth and fifth centuries. It commemorates the triumph of the party that secured the use of images over the iconoclasts; this was the ‘orthodoxy’ which was chiefly celebrated; and we can fix the date of the establishment of the festival as A.D. 842. Again, the commemoration of All Souls in the West was the outcome of a growing sense of the need of prayers and masses on behalf of the faithful departed. The ninth century shows traces of the observance of some such day; but it was not till the close of the tenth century, under the special impetus supplied by the reported visions of a pilgrim from Jerusalem, who declared that he had seen the tortures of the souls suffering purgatorial fire, that the observance made headway. We then find Nov. 2 assigned for the festival, which came to be gradually and slowly adopted. The feast of Corpus Christi, which now figures so largely in the popular devotions of several countries of Europe, and is marked as a ‘double of the first class’ in the service-books of the Church of Rome, emerges for the first time in the thirteenth century, and was not formally enjoined till the fourteenth. The feast of the Conception of St Mary the Virgin seems to have originated in the East, and to have been simply a historical commemoration, even as the Greeks commemorate the conception of St John the Baptist. The Eastern tradition represents Anna as barren and well stricken in years, when, in answer to her prayers and those of Joachim her spouse, God revealed to them by an angel that they should have a child. This conception was according to the Greek Menology ‘contrary to the laws of nature,’ like that of the Baptist. In the West the festival of the Conception appears at the end of the eleventh or beginning of the twelfth century. The controversies as to its doctrinal significance form part of the history of dogma, and are full of instruction: but they cannot be considered here. Up to the year 1854 the name of the festival in the Kalendars of the authorised service-books of the Roman Church was simply _Conceptio B. Mariae Virginis_. It was as recently as Dec. 8, 1854, by an ordinance of Pope Pius IX, that the name was changed into _Immaculata Conceptio B. Mariae Virginis_. It will thus be seen how changes in the Kalendar illustrate the changes and accretions of dogma, facts which are further exhibited by the changes in the rank and dignity of festivals of this kind, at first only tolerated perhaps, and of local usage, but eventually enjoined as of universal obligation,