The entire number of ecclesiastical holydays and seasons is codified for us in the different Church calendars. Their contents fall into two essentially different divisions, each possessing an entirely different origin and history. The first division consists of festivals of our Lord, distributed over the year, regulated and co-ordinated in accordance with certain laws. The second division consists of commemorations of saints in no wise connected with festivals of our Lord or with one another. Occupying to some extent an intermediate position between these two chief divisions come the festivals of our Blessed Lady, which have this in common with the festivals of the saints, that they fall on fixed days; but, on the other hand, they are to a certain extent connected with each other and with some feasts of our Lord. This is carried out in such a way that they are distributed throughout the Church year and are included in each of the festal seasons (Kellner, _Heortology_, Part I.). From Apostolic times the feasts of Easter, the Ascension and Pentecost were celebrated. In the second century feasts of the Apostles were celebrated and the cult of the Martyrs was of speedy and widespread development. But it was not, probably, till the fourth century, that the feasts of saints who were not martyrs were celebrated. _Origin of the different grades of feasts_. To-day, we find Church festivals arranged in three grades, doubles, semi-doubles and simples, and it is very difficult, to determine clearly and accurately the origin and the nature of the arrangements. But from the works of scholars, who have studied this matter, the following may be considered as a fair and accurate summing up:-- In the first ages of the Church the Apostles and Martyrs only were commemorated in public prayers and, above all, in the Mass, perhaps, by a special prayer. Then, in time, followed the reading of a panegyric in their honour, and later still hymns and histories of martyrdom were added to the public recitation of the Office. Still later, there were added the feasts of the saints with an office resembling our simple office. Matins were entirely ferial, but had either a biography of the saint or a long extract from the Fathers added. The other hours were as in a Sunday office, save that these feasts had no Vesper matter.