Catholic Encyclopedia (1913)/Assistant Priest
The assistant priest (presbyter assistens, anciently called capellanus) is the first and highest in dignity of the ministers who assist the bishop in pontifical functions. Where there are cathedral chapters, ordinarily the first dignitary acts as assistant priest; but if the bishop only assists at a service, then the first canon after the dignitaries should serve in this capacity. If a priest preaches at pontifical Mass, the preacher should also be assistant priest. A cardinal-bishop acts as assistant priest for the pope. By privilege, prothonotaries de numero participantium and mitred abbots may have an assistant priest when they celebrate pontifical Mass; and so also, but with some restrictions, supernumerary prothonotaries and prothonotaries ad instar. Certain dignitaries and canons in virtue of ancient custom are similarly privileged, and finally the Sacred Congregation of Rites tolerates the custom of having an assistant priest at a priest's first solemn Mass. While assisting the celebrant the assistant priest wears the cope and amice over his surplice or rochet; but while assisting the bishop presiding at the throne he wears his regular choral dress. At the throne his stool is place on the platform of the throne, regularly at the right and a little in front of the first assistant deacon. When the celebrant uses the faldstool, the assistant priest sits on the bench at the deacon's right; but when the celebrant uses the bench, the assistant priest sits on a stool placed at the end of the bench and usually at the right of the deacon. His chief duty is to attend to the book, which he holds for most of the parts which the celebrant sings, and at the altar he turns the leaves, points out the text, etc. He ministers the ring, presents the towel, and receives the kiss of peace first, from the celebrant, and conveys it to the choir. At the throne he also ministers the incense and incenses the bishop. Sometimes it is his duty to publish the episcopal indulgences. When the bishop presides at the throne, part of the time the assistant priest occupies his place at the throne, and part of the time his regular place in the choir, and then he ministers the incense, incenses the bishop, and brings the kiss of peace from the celebrant to the bishop. In other pontifical functions besides the Mass and the Divine Office his duties are similar to those described.
Caeremoniale Episcoporum (Ratisbon, 1902); MARTINUCCI, Manuale sacrarum caerimoniarum (Rome, 1879); DE HERDT, Praxis pontificalis (Louvain, 1904); LE VAVASSEUR, Les Fonctions pontificales (Paris, 1904); Ceremonial of the Church (Philadelphia, 1894) 313.