This monogram is formed, as will be perceived, by the combination of the Greek characters CHI and RHO, the first two letters of the word ΧΡΙΣΤΟΣ, or Christ. It may, indeed, be regarded rather as a contracted form of writing that word than as a proper symbol, just as we sometimes write Xt. and Xmas. for Christ and Christmas. Indeed, it most probably originated in the prevalent practice of contracted and monogrammatic writing, of which we have so many examples in these inscriptions. That the monogram stands for the name of Our Lord will be apparent from an examination of a few of the inscriptions in which it occurs, as, for instance, the very first dated example, above given. See also the following: IN PACE ET IN ☧ DEO--“In peace and in Christ God;” BIBAS IN ☧--“May you live in Christ;” IN ☧ VICTRIX, which probably meant “Victrix (a woman’s name) victorious in Christ.” Marangoni gives the accompanying impression of a seal on the plaster of a grave. See figure 56. [Illustration: “Hope in Him,” _i. e._, in Christ. Fig. 56.--Christian Seal.] This monogram soon became almost universal in the Catacombs, on sepulchral slabs, lamps, vases, rings, seals, weights, gems, etc., and in every conceivable modification of form, some of which are shown in the illustration on next page. See also the vignette on title page, copied from an alabaster slab in the Collegio Romano, originally from the Catacombs. [Illustration: Fig. 57.--Various Forms of the Constantinian Monogram.] [Illustration: Fig. 58.--“Tasaris in Christ, the First and the Last.”] Frequently the Greek letters Alpha and Omega accompany the monogram, as in numbers 1, 4, and 6 of Fig. 57, in allusion to the sublime passage in the Revelation descriptive of the eternity of Christ.[447] 267 Sometimes the order of the letters is reversed, probably through the ignorance of the artist, as in the accompanying rude example, Fig. 58. The whole was sometimes placed obliquely, or even turned upside down, doubtless for the same reason. Even in its simplest form it was considered sufficient to give a Christian character to a tombstone which had been originally pagan. Such inscriptions are called 268 _opisthographæ_, that is, written behind. In the following example from Aringhi the letters D. M., for the heathen formula DIS MANIBVS,--“To the Divine Manes,” are partially obliterated, and the consecrating sign substituted instead. [Illustration: Fig. 59.--Opisthographic Inscription.]