Ecclesiarch

A sacristan is an officer charged with care of the sacristy, the church, and their contents.

In ancient times, many duties of the sacristan were performed by the doorkeepers (ostiarii), and later by the treasurers and mansionarii. The Decretals of Gregory IX speak of the sacristan as if he had an honourable office attached to a certain benefice, and say that his duty was to care for the sacred vessels, vestments, lights, etc. Nowadays the sacristan is elected or appointed. The Cæremoniale Episcoporum prescribed that in cathedral and collegiate churches the sacristan should be a priest, and describes his duties in regard to the sacristy, the Blessed Eucharist, the baptismal font, the holy oils, the sacred relics, the decoration of the church for the different seasons and feasts, the preparation of what is necessary for the various ceremonies, the pregustation in pontifical Mass, the ringing of the church bells, the preservation of order in the church, and the distribution of Masses; and finally it suggests that one or two canons be appointed each year to supervise the work of the sacristan and his assistants.

The under-sacristan (custos) is also mentioned in the Decretals. He was the assistant of the sacristan, was subject to the archdeacon, and discharged duties very similar to those of the sacristan. By the early twentieth century the office was hardly ever attached to a benefice and so usually a salaried position. The Council of Trent desired that, according to the old canons, clerics should hold such offices; but in most churches, on account of the difficulty or impossibility of obtaining clerics, laymen perform many of the duties of the sacristan and under-sacristan.

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Wikipedia