In so far as Thomas left a great legacy, it was as a saint rather than as a politician. By the time that Henry performed his penance at Thomas’s tomb, Thomas had officially been recognized martyr for the faith. After some investigation of claims that Thomas was performing miracles, Pope Alexander III formally canonized him on February 21, 1173, less than 26 months after his death, a remarkably short interval for a canonization. The veneration of the new martyr spread with notable rapidity around Europe. No earlier medieval saint’s cult spread anything like as fast, and only Saint Francis of Assisi compares among later saints. Thomas’s cult remained a major one for centuries, celebrated in architecture, art, music, the liturgy, and plays. In Scotland, the abbey of Arbroath, founded by King William the Lion in 1175, was dedicated to Thomas. The spread of veneration for him on the Continent was undoubtedly helped by the marriages of three of Henry Il’s daughters to rulers of foreign lands: Joan married first in Sicily and then in southern France, Matilda in Germany, and Eleanor in Spain. Thus, possibly the earliest known representation in art of Saint Thomas of Canterbury is a mosaic in the church of Monreale in Sicily, which may have been done as early as sometime between 1174 and 1182, probably after Joan of England’s marriage to William of Sicily in 1177. By about 1190, a stained-glass window in Sens cathedral depicted scenes from Thomas’s life; from about 1206 comes a window in Chartres cathedral, to which John of Salisbury, as bishop of Chartres between 1176 and his death in 1180, had given two vials of Saint Thomas’s blood. Relics of Saint Thomas were distributed very widely, and, for most of the thirteenth century, the great French center of enamelware at Limoges turned out small chests, most of them intended as reliquaries, depicting the scene of the murder, often accompanied by the scene of the saint’s burial. More of these chests survive of Thomas than of any other saint. From Scandinavia to Iceland to Spain to Rome to the Holy Land, churches and chapels were dedicated to Saint Thomas.
At least 184 sermons on him survive from between the 1170s and about 1400; the preachers whose nationalities are known were English, French, Italian, Portuguese, German, Austrian, and Polish. Thomas became the patron saint of the London Company of Brewers and the Venetian wine coopers. By the early sixteenth century, if not earlier, the tale of Saint Thomas was the subject of popular plays: a pageant was performed annually at Canterbury from 1504 until the suppression of Thomas’s cult and revived under Queen Mary; in 1519 Becket’s life was the subject of a pageant in the London midsummer show. These are only a few of the examples of the ways in which Saint Thomas of Canterbury became one of the most famous saints in all of Europe.