This reliquary bust was probably made to house a relic of Saint Louis, Bishop of Toulouse (1274–97), second son of Charles II of Anjou, King of Naples (1288–1309). Renowned for his works of charity, he was made bishop in 1297 and died shortly after at the age of 23. He was canonized in 1317, and his cult of veneration spread rapidly in Italy and Spain. In art, Louis is generally represented as a "boy" bishop without a beard and with youthful features. The relic (now lost) would have been enshrined within. On feast days the reliquary would have likely been carried in procession and otherwise placed in a church sanctuary or on a side altar for the veneration of the faithful.

Relics were the physical remains of the saints, chiefly their bodies. The living venerated the relics of the saints in order to seek their patronage, which in turn provided a proximate link to the divine ruler. The power of the saints was therefore manifested by and through their relics, or objects that were owned or touched by them. Medieval pilgrims, in a world fraught with peril, sought close physical contact with relics, which protected both the spiritual and temporal welfare of laypeople and religious communities.