Catholic Encyclopedia (1913)/Pectorale
The name of the cross used by the pope, cardinals, bishops, abbots, and other prelates entitled to use the pontifical insignia. It is worn on the breast attached to a chain or silken cord, the colour differing, according to the dignity of the wearer, i.e. green, violet, or black. It is made of precious metal, ornamented, more or less, with diamonds, pearls, or similar embellishment, and contains either the relics of some saint, or a particle of the Holy Cross. It is worn over the alb during liturgical functions. The prelate should kiss the cross before putting it on his neck, and while putting it on say the prayer "Munire me digneris" (the origin of which dates back to the Middle Ages), in which he petitions God for protection against his enemies, and begs to bear in mind continually the Passion of Our Lord, and the triumphs of the confessors of the Faith. The pontifical pectoral cross is distinct from the simple cross, the use of which is often permitted by the pope to members of cathedral chapters. Canons, to whom this privilege has been granted, are permitted to wear the cross at choir service only, and not over the alb at liturgical services, unless specially permitted. The pectoral is the latest addition to episcopal ornaments. The custom, however, of wearing a cross on the breast either with or without holy relics, dates back to ancient time and was observed not only by bishops, but also by priests and lay people. The first mention made of the pectoral cross as a part of pontifical ornament is made by Innocent III, and its use as such only became customary toward the close of the Middle Ages. As an adornment for bishops we meet it the first time toward the end of the thirteenth century (Durandus), but at that time it was not generally worn by bishops. As Durandus says: "it was left to the discretion of the individual bishop to wear it or not". The Greek bishops also wear a pectoral cross but only over their liturgical vestments (chasuble or salkos).