The mystic significance of the episcopal ring as typifying the union of Christ with his Church was expressed by Innocent III (1198–1216) in these words: “The ring is a sacrament of faith, by which Christ endows his spouse the Holy Church.”[439] This can be taken as confirmatory of the theory that the episcopal rings were directly derived from the betrothal rings, and were not merely attributes of ecclesiastical rank. So closely was the Bishop bound to his see, that his abandonment of it to go to another was regarded by some as equivalent to the commission of adultery. A fine example of a sapphire-set episcopal ring was found in 1844, during some alterations to the chapel of Notre Dame in the Cathedral of Troyes. Several stone coffins were discovered, among them that containing the remains of Hervée, Bishop of Troyes, consecrated in 1206. The body was clothed in full episcopal vestments. The ring had fallen from the hand but was found at the left side of the body. It had a diameter of 2 cm. (about ⅘ inch) and was set with a fine oblong sapphire held in place by four claws.[440] The opening of the tomb of Pope Boniface VIII (1294–1303) revealed the presence, on the gloved hand of the dead pope, of a splendid gold ring, set with a sapphire of quite exceptional size and beauty.[441] In 1804, at the opening of a thirteenth-century archbishop’s sepulchre in the Cathedral of Mainz, believed to be that of Archbishop Sigfroi III, 1249, a fine pontifical ring was found; it is set with a large ruby.[442] The bezel is of disproportionate size in comparison with the dimensions of the rather slender circlet.[443] This ring is large enough to be worn over a glove in accord with liturgical requirements. It has been noted that in process of time the width and thickness of the circlet were gradually increased, at first to make it harmonize better with a large bezel; gradually, however, both bezel and hoop were made so large as to render the ring a burden to the wearer, and even difficult to keep from slipping off the finger. Indeed, it was sometimes necessary to wear a second, closer-fitting ring _under_ it as a guard.[444] The treasury of Canterbury Cathedral contained in 1315, according to an inventory of the “Ornamenta Ecclesiastica,” a very rich and elaborate pontifical ring. It is described as a large square ring, set with an oblong emerald, four plasmas (leek-green quartz), and four garnets. The other episcopal rings listed on this inventory were set with sapphires bordered with small gems, one of them having a “black sapphire” set _à jour_, and held in place by claws. While at this period great latitude was exercised regarding the particular stone to be chosen for the chief adornment of the ring, it was required that it should be one of the more precious stones.[445]