(MONSTRUM, OSTENSORIUM) is a vessel used for the preserving of relics, and particularly for the consecrated host (sanctissimumn, vensersabile, eucharistia), and in which they are presented to the adoration of the people. When, in the 13th century, the doctrine of transubstantiation was established by the Church, the elevation of the host followed, as also its special exhibition, for instance, in the procession of Corpus-Christi Day (q.v.). For that purpose the host (q.v.) was placed on a curved surface
(lunula), and introduced in a transparent vessel (monstrantia, in qua sub vitro crystallino cruor inclusus [Du Fresne, Glossar. s.h.v.]). This case (phylacterium, arcula) is enlarged by the addition of rays, forming an image of the sun, or the like, and provided with a stand. It is placed on the altar. Thus the monstrantia becomes a movable shrine for the sacrament (taberncaculum gestatoriumn), generally made of costly material, and richly decorated. "At first," says Walcott (Sacred Archaeology, page 390), "it took the shape of an ordinary reliquary, but at length was made like a tower of crystal, of cylindrical form, and mounted on a foot like that of a chalice, and covered by a spire-like canopy, with flying buttresses. Inside the cylinder was a crescent held by an angel, in which the host was set: in some cases the cylinder was replaced by a quarterfoil, or was surrounded by a foliage like a jesse-tree, and at a later date by the sun, a luminous disk, with rays alternately straight and wavy, set upon a stand. Upon the vessel itself the Doom was often represented, and relics were placed in it. The monstrance did not become common till the 15th, and is probably not earlier than the 14th century. It bore different forms: (1) a little tower, jewelled, and having apertures of glass or crystal; (2) the figure of a saint, or the Holy Lamb, with St. John the Baptist pointing to it; (3) a cross; (4) a crystal lantern, or tube, mounted on a pedestal of precious metal, and covered with a canopy in the 15th century; (5) a sun, with rays, containing in the centre a kind of pyx (this is found as early as the 16th century)." The ecclesiastical laws now regulate its construction. The statutes of the archbishopric of Prague of 1605, tit. 18, command, for instance, "Monstrantia ad exponendam vel in processionibus deferendam hostiam magnam, si non ex auro, aut argento, saltern ex aurichalco bene aurato refulgeat, et velo vel peplo congruo ornata sit." The monstrantia is a sacred vessel, and not to be touched by an unconsecrated person; hence any one who stole it was to be burned to death. The high altar is always provided with a monstrantia, and often the side altars also. All evangelical churches have rejected the prayer De venerabile of the Romish Church, and Luther declared, "It is insulting and dishonoring to the holy sacrament to carry it about, and to make it an instrument of idle idolatry." See also Herzog, Real-Encyklopadie, 9:757.