Celtic Rite
The term "Celtic Rite" is applied to the various liturgical rites used in Celtic Christianity in Britain, Ireland and Brittany and the monasteries founded by St. Columbanus and Saint Catald in France, Germany, Switzerland, and Italy during the Early Middle Ages. The term is not meant to imply homogeneity; instead it is used to describe a diverse range of liturgical practices united by lineage and geography.
Welsh church
Before the 8th century AD there were several Christian rites in Western Europe. Such diversity of practice was often considered unimportant so long as Rome's primacy was accepted. Gradually the diversity tended to lessen so that by the time of the final fusion in the Carolingian period the Roman Rite, its Ambrosian variant, and the Hispano-Gallican Mozarabic Rite were practically all that were left.British bishops attended the Council of Arles in A.D. 314 and the Council of Rimini in 359. Communication with Gaul may be inferred from dedications to St. Martin at Whithorn and at Canterbury, from the mission of Victridius of Rouen in A.D. 396 and those of Germanus of Auxerre, with St. Lupus in 429 and with St. Severus in 447, directed against the Pelagianism of which the bishops of Britain stood accused.
However much of Britain derived their religion from Irish missionaries. Aidan of Lindisfarne, Foillan, Diuma, Finan of Lindisfarne, Jaruman and others evangelised the Anglo-Saxons. Ia of Cornwall and her companions, Saint Piran, St. Sennen, Petroc came to Cornwall and probably brought with them whatever rites they were accustomed to. Cornwall had an ecclesiastical quarrel with Wessex in the days of St. Aldhelm, which appears in Leofric's Missal, though the details of it are not specified.
The certain points of difference between the British Church and the Roman in prior to Bede were: The rule of keeping Easter the tonsure the manner of baptizing. Gildas also records elements of a different rite of ordination.
Liturgy
There is a Mass, probably of the 9th century, apparently Cornish since it mentions "Ecclesia Lanaledensis" and in honour of St. Germanus. It is quite Roman in type, probably written after that part of Cornwall had come under Saxon influence, but with a unique Proper Preface. The manuscript also contains glosses, held by Professor Loth to be Welsh but possibly Cornish or Breton. There is little other evidence as to what liturgy was in use.Anglicans of the 19th century such as Sir William Palmer in his Origines Liturgicae and the Bishop of Chichester in his Story of the English Prayerbook proposed that Irenaeus, a disciple of St. Polycarp the disciple of St. John the Divine, brought the Ephesine Rite to Provence whence it spread through Gaul to Britain and became the foundation of the Sarum Rite.
The Ephesine origin of the Gallican Rite rested first upon a statement of Colmán of Lindisfarne in 664 at the Synod of Whitby respecting the origin of Easter and second upon an 8th-century Irish writer who derived the divine office from Alexandria. Archbishop Nuttall also asserted the Eastern origin of the Irish rite. The Catholic Encyclopedia disagreed, asserting that the Sarum Rite is "merely a local variety of the Roman, and that the influence of the Gallican Rite upon it is no greater than upon any other Roman variety".
A letter from Pope Zachary to St. Boniface, and in cap. ix of the same book, after ordering the reordination of those ordained by Scottish and British bishops "who are not Catholic in their Easter and tonsure" and the asperging of churches consecrated by them. It has been conjectured that the British Church resembled the Hispanic in baptizing with a single immersion. This form had been allowed by Rome in the case of Iberia.
Celtic Passover versus Roman Easter
The Irish, the English, and the Britons adhered to the Jewish Passover instead of Easter Sunday. They adhered to moon phases and counted the third week of the moon from the 14th to the 20th instead of from the 15th to the 21st.Colman at the Synod of Whitby may have had the Quartodeciman controversy in mind when he claimed an Ephesian origin for the Irish calculations of Passover. St. Wilfrid answered that according to the Quartodeciman rule Passover might be kept on any day of the week, not just a Sunday, whereas the Irish and those they had evangelised kept it on Passover only. St. Aldhelm in his letter to King Gerontius of Dumnonia also seems to charge the Cornish with Quartodecimanism.
The Easter versus Passover question was eventually settled at various times in different places. The following dates are derived from Haddan and Stubbs: Western, eastern and southern Ireland, 626-8; northern-west Ireland, 692; Northumbria, 664; East Devon and Somerset, 705; the Picts, 710; Iona, 716-8; Strathclyde, 721; North Wales, 768; South Wales, 777. Cornwall held out the longest of any, perhaps even, in parts, to the time of Bishop Aedwulf of Crediton.
Establishment of the Irish Rite
There were Christians in Ireland before Saint Patrick, but we have no information as to how they worshipped, and their existence is ignored by Tirechan's 7th-century Catalogus Sanctorum Hiberniae, which divides the saints of Ireland into three orders covering about 225 years from the coming of St. Patrick in 440 in the reign of Laoghaire MacNeil to the reign of Blathmac and Diarmait sons of Áed Sláine in 665. Each order is stated to have lasted for the reigns of four kings - symmetry is attained by omitting about six intervening reigns, but the outside dates of each period are clear enough, and the document relates customs of the Divine Office and the Easter and tonsure questions.The first order was in the time of Saint Patrick, from the reign of Laoghaire to that of Túathal Máelgarb. They were all bishops, 350 in number, founders of churches, all Romans, French, Britons and Scots. They had one Head, Christ, one leader, Patrick, one Mass and one tonsure from ear to ear and they celebrated Easter a fortnight after the spring equinox.
The second order was of few bishops and many priests, 300 in number. It lasted from the end of the reign of Tuathal to that of Áed mac Ainmuirech. They had one head, Christ, they celebrated different Masses and different rules, they had one Easter, the fourteenth of the moon after the equinox, and one tonsure from ear to ear. They received a Mass from the Britons, David of Wales, Gilla, and Docus. The Life of Gildas tells how King Ainmuire mac Sétnai sent for Gildas to restore ecclesiastical order in his kingdom in which the Catholic faith was being laid aside.
The third order were priests and a few bishops, 100 in number, living in wildernesses on an ascetic diet, evidently hermits and monks. They had different Masses, different rules, and different tonsures,, and celebrated different Easters, some on the fourteenth, some on the sixteenth, of the moon "with hard intention" which perhaps means "obstinately". These lasted from the reign of Áed Sláine to that of his two sons Diarmait and Blathmac.
The "unam celebrationem" of the first order and the "diversas regulas" of the second and third probably both refer to the Divine Office. The meaning seems to be that the first order celebrated a form of Mass introduced by Patrick, who was the pupil of Germanus of Auxerre and Honoratus of Lerins, perhaps a Mass of the Gallican type. The 8th-century tract in Cott. MS. Nero A. II states that St. Germanus taught the "Cursus Scottorum" to St. Patrick. It is clear that the British Mass introduced by David, Gildas, and Cadoc differed from it. The second and third orders used partly Patrick's Mass and partly one of British origin, and in the case of the third order Roman modifications were also introduced.
The working of the "Catalogus" seems to imply that the first and second orders were Quartodecimans, but this is clearly not the meaning, or on the same argument the third order must have been partly Sextodecimans – if there were such things – and moreover we have the already mentioned statement of St. Wilfrid, the opponent of the Celtic Easter, at the Synod of Whitby, that such was not the case. Tirechan can only mean what we know from other sources: that the fourteenth day of the moon was the earliest day on which Easter could fall, not that it was kept on that day, Sunday or weekday. It was the same ambiguity of expression which misled Colman in 664 and St. Aldhelm in 704. The first and second orders used the Celtic tonsure, and it seems that the Roman coronal tonsure came partly into use during the period of the third order.
After that we have an obscure period, during which the Roman Easter which had been accepted in South Ireland in 626–628, became universal, being accepted by North Ireland in 692, and it seems probable that a Mass on the model of the Carlsruhe and Piacenza fragments and the Stowe and Bobbio Missals - a Roman Canon with some features of a non-Roman type - came into general use. It was not until the 12th century that the separate Irish Rite, which, according to Gilbert, Bishop of Limerick, was in use in nearly all Ireland, was abolished. Saint Malachy, bishop of Armagh, began the campaign against it, and at the Synod of Cashel, in 1172, a Roman Rite "juxta quod Anglicana observat Ecclesia" was finally substituted.
Scottish sources
In Scotland there is very little information. Intercourse with Ireland was considerable and the few details that can be gathered from such sources as Adamnan's Life of St. Columba and the various relics of the Scoto-Northumbrian Church point to a general similarity with Ireland in the earlier period. Of the rite of the monastic order of the Culdees very little is known, but they certainly had a rite of their own, which may have been similar to the Irish.The Roman Easter and tonsure were adopted by the Picts in 710, and at Iona in 716–18, and much later, in about 1080, St. Margaret of Scotland, wife of King Malcolm III, wishing to reform the Scottish church in a Roman direction, discovered and abolished certain peculiar customs of which Theodoric, her chaplain and biographer, tells us less than we could wish.
It seems that the Scots did not begin Lent on Ash Wednesday but on the Monday following, as is still the Ambrosian practice. They refused to communicate on Easter Day and arguments on the subject make it seem as if the laity never communicated at all. In some places they celebrated Mass "contra totius Ecclesiae consuetudinem, nescio quo ritu barbaro". The last statement may be read in connection with that in the Register of St. Andrew's, "Keledei in angulo quodam ecclesiae, quae modica nimis est, suum officum more suo celebrant".
How much difference there may have been cannot be judged from these expressions. Scotland may have retained a primitive Celtic Rite, or it may have used the greatly Romanized Stowe or Bobbio Mass. The one fragment of a Scottish Rite, the Office of the Communion of the Sick, in the Book of Deer, probably 11th century, is certainly non-Roman in type, and agrees with those in the extant Irish books.
The Book of Deer is a 10th-century gospel book from Old Deer, Aberdeenshire, Scotland, with early 12th-century additions in Latin, Old Irish and Scottish Gaelic. Now in the Cambridge University Library. It contains part of an order for the communion of the sick, with a Gaelic rubric. The origin of the book is uncertain.