Today, December 31, is the feast of Pope Silvester I, famous for converting Constantine the Great to Christianity and for defeating a pestiferous dragon hiding in the caverns beneath Rome. However, this blogpost is not about the sainted pope, but about the sainted archbishop Thomas of Canterbury, popularly known as Thomas Becket, who was appointed by King Henry II to the see of Canterbury, was sent into exile in 1164, and was murdered by knights at the altar of Canterbury Cathedral in 1170 within a year of having returned to England and been reconciled with the king. Thomas was canonised by Pope Alexander III in 1173, lives and liturgical offices were soon written in his honour, and his cult spread to the various corners of the Latin West.
Thomas of Canterbury going into exile
BL MS Royal 2 B VII, psalter, between 1310 and 1320
One of the corners in which the cult of Thomas of Canterbury achieved great popularity was the Norwegian metropolitan see of Trondheim, the centre of the Nidaros Archbishopric which - by the turn of the twelfth century - covered mainland Norway, Iceland, the Faroe Islands, Greenland, Orkney, Shetland, and the South Islands (Hebrides and Man). The popularity of Thomas in Norway was owed in large part to the circle around Archbishop Eystein Erlendsson (r.1161-88) and his successors, who belonged to the same school of ecclesiastical thought as did Thomas of Canterbury, and also Pope Alexander III. These high-ranking ecclesiastics all embraced the reformist ideals that had been formulated in the course of the Gregorian Reform Movement in the eleventh century also throughout the twelfth century.
We do not know exactly how and when the liturgical celebration of Thomas of Canterbury arrived in Norway, or who brought the liturgical texts that were used, but there were many points of contact between the Norwegian and the English churches in the twelfth century. Moreover, the metropolitan see in Trondheim were probably eager recipients of the cult of Thomas as this gave them another saintly patron in their efforts to establish a Gregorian ideal kingdom in which the king was subject to the church and not the other way around. These efforts were cut short, however, when the pretender Sverre made claims to the throne and emerged victorious in the civil war that raged from 1177 to 1184. Despite this victory, King Sverre and the Norwegian clergy continued to quarrel about the relationship between king and church, and this conflict is likely to have strengthened the importance of Thomas of Canterbury in the Norwegian church province.
There is much to be said about the liturgical celebration of Thomas of Canterbury in Norway, but for the time being I will restrict myself to one single commemoration to exemplify his importance. The commemoration in question is found in the Ordo Nidrosiensis Ecclesiae, a collation of manuscripts from the Nidaros province in which there are found rubrics and notes regarding the details of the liturgical celebrations of the Nidaros churches. It was edited in 1968 by the Norwegian medievalist Lilli Gjerløw.
In the details for the feast of Saint Silvester on December 31, under the heading of the office of Lauds (around daybreak), a number of antiphons are listed that are to be performed in commemoration of important saints of the Christmas season. Among these were Stephen Protomartyr whose feast was on the 26th of December, the child martyrs of Bethlehem whose feast was on the 28th of December, and Thomas of Canterbury whose feast was on the 29th of December.
While the liturgical office, typically attributed to Benedict of Peterborough, was used for the celebration of Thomas' feast in Nidaros, the antiphon used for his commemoration is not from this repertoire but instead from the common of one martyr. These texts from the common of a type of saints comprised a shared repertoire of liturgical chants that were accessible to all of Latin Christendom. When a chant from this common material was used in the celebration of a specific saint, and especially a saint who had been added to the liturgical calendar in recent times, the individual saint's place among his saintly colleagues was emphasised. In the case of Thomas of Canterbury in Nidaros, the chant from the common of martyrs emphasised that he belonged in the collegium of martyrs who had been martyred alone - as opposed to the martyrs who had died as a group (although links between various types could be established through chant as well).
The antiphon by which Thomas of Canterbury was commemorated, was Nisi granum frumentum (CID 003883). The text of this chant is as follows:
Nisi granum frumenti cadens
in terra mortuum fuerit ipsum solum manet
The antiphon applies the imagery of the grain that is being threshed and in that process is being refined. In the liturgy of martyrs, as well as other saints, it was very common to apply imagery that invoked various labours of refinement. This is also seen in the office composed specifically for Thomas of Canterbury, where one responsory describes the exile of Thomas as a gem that is being hammered for six years, meaning that this hardship was part of what proved Thomas' sanctity.
That the antiphon Nisi granum was used in the Nidaros Archdiocese to commemorate Thomas of Canterbury on Saint Silvester's day, is just one of the many examples of Thomas' importance to the Norwegian clergy. It is as yet unclear whether such a commemoration, and this antiphon in particular, was established in the Norwegian liturgy by the metropolitan clergy, or whether it was a practice that was brought from overseas. The latter is more likely, because in the context of the reform movement the clerics sought unity and adaptation of existing practices, not originality or uniqueness. Together with other commemorations throughout the Christmas season in the Nidaros liturgy, the antiphon Nisi granum demonstrates that the cult of Thomas of Canterbury was of great importance in the Norwegian church province.