LABARUM. — It is the standard made by the emperor Constantine himself after having seen a luminous cross with the inscription τούτῳ νίκα.
The description of the standard itself, according to the *Vita Constantini* (I, 31), is as follows. It consisted of a long pole covered in gold, which at the top had a crossbeam in the form of a cross. At the summit was fixed a crown of precious stones enclosing the two letters, while the bed of the name XP(ιστός) was intertwined so that the upright of the P was cut through the center of the X. To the pole was attached a purple cloth of regal magnificence, square in shape, woven with gold and precious stones; beneath the cloth, later added, were medallions of Constantine and his sons.
The *Vita Constantini* places the vision in Gaul; it is well known how much its authenticity is disputed (v. Eusebio di Cesarea, II, Opere storiche); but the vision is attested, besides by Eusebius himself (Hist. eccl., IX, 1-11), by two panegyrics, one from 313 and the other from 321. Moreover, Lactantius speaks of a dream at the gates of Rome, before the battle ad Saxa Rubra (De mortibus persecutorum, 44). According to a version reported by Rufinus (Hist. eccl., IX, 9, 1) and later by Socrates (Hist. eccl., I, 3), Constantine would have heard from angels in his dream the words τοῦ νίκα. Philostorgius (Hist. eccl., I, 6) relates that the Cross appeared amid an iridescence of stars which formed the words in hoc vince, in Latin. Eusebius, in his history (IX, 9, 10), describing the statue erected by Constantine in memory of the battle of the Milvian Bridge and the triumph over Maxentius, says that the Emperor was depicted holding the Labarum. H. Grégoire has highlighted the importance of Rufinus’s text regarding the inscription placed beneath the statue of Constantine in the Roman Forum: *in hoc singulari signo quod est vere virtutis insigne*, to demonstrate that it was a true standard, a *vexillum* (La statue de Constantin et le signe de la Croix, in *L'antiquité classique*, I [1932], pp. 135-43). St. Ambrose in 388 calls the Labarum *Christi sacratum nomine* (Ep. 40: PL 16, 1152); shortly afterward, Prudentius writes that *Christus purpureum gemmati textus in auro signabat labarum, clypeorum insignia Christi scripserat* (Contra Symmachum, I, 487-89). Paulinus of Nola describes the monogram of Christ and explains its composition through the two letters chi and rho (Poem., XIX: PL 61, 612-27). Based on Eusebius’s text, G. Wilpert reconstructed the Labarum (cf. *Vision und Labarum Konstantins des Grossen*, Cologne 1913), a reconstruction he later published in color, having re-examined the data from Eusebius, Lactantius, and the monuments (cf. *Mosaiken*, pp. 28-52 and pl. 51, 2).
A fine documentation on the Labarum and some of its variants is provided by Constantinian numismatics. The monogram is the same *coeleste signum Dei* recalled by Lactantius in his *De mortibus persecutorum*, seen in a dream by Constantine and painted on the shields of the soldiers and placed on Constantine’s helmet. The mint of Siscia struck in the year 317 a coin with the monogram on Constantine’s helmet. A coin in the Numismatic Cabinet of Vienna, published by G. Wilpert (*Mosaiken*, p. 33, fig. 2) and by A. Alföldi, shows the monogram very clearly on the Emperor’s helmet (A. Alföldi, *The helmet of Constantine, with the christian monogram*, in *Journal of Roman Studies*, 22 [1932], pp. 9-23, pl. 4,17). A coin of Vetranio presents the Labarum with the monogram in the center of the cloth and the inscription *Hoc signo victor eris* around it (Wilpert, *Mosaiken*, p. 42, fig. 9). That this monogram is the *Signum Christi* is attested by a graffito in the cemetery of Priscilla in which, after wishing the deceased Gregory and Sabbatia “in pace,” the explanation of the monogram is added: *signum Christi* (Wilpert, *Mosaiken*, 29 and photographic reproduction in *Sarcofagi*, fig. 201).
But the Labarum with the monogram in the center of the cloth is found on a fifth of Constantine and on medallions of Constantine. A coin of Constantine shows the Labarum with the monogram without the crown at the top of the pole planted in the ground crushing a serpent (Wilpert, *Mosaiken*, p. 37, fig. 5). Instead, in the celebrated diptych of Aosta, on the cloth of the Labarum held by the emperor Honorius is written: *in nomine XPI vincas semper*; and the monogram is found at the end of the pole within the crown. Recently H. Grégoire, after studying *L'Etymologie du Labarum* (in *Byzantion*, 4 [1929], pp. 477-82) and denying that Eusebius is the author of the *Vita Constantini* (ibid., 13 [1938], pp. 561-83), believes he can dismiss Constantine’s vision as well (*La vision de Constantin «liquidée»* (ibid., 14 [1939], pp. 341-51); to him J. Zeiller responded (*Remarques sur la vision de Constantin*, ibid., 14 [1939], pp. 331-39) and A. Alföldi (*The conversion of Constantine and Pagan Rome*, Oxford 1948, pp. 16-17). Even on a stele from Larissa in Macedonia the monogram surrounded by a crown is called *signum Christi* (CIL, III 7315); the monogram found in St. Agnes has also *in hoc signo... vincas* (G. B. De Rossi, *Cimitero di S. Agnese*, in *Bull. di arch. christ.*, 2a serie, 6 [1875], pp. 80-82); as also in the inscription of Sinfonia seen by A. Bosio: *in hoc vincas* and beneath the monogram (A. Bosio, *Roma sotteranea*, Rome 1632, p. 215). At Sicca Veneria (now El-Kef in Tunisia) around the Cross with the letters alpha and omega is written: *in hoc signum semper vincas* (CIL, VIII, 1767); at Deir-Sanbil, in Syria, beneath the words *TOYTῼ NIKA* are engraved two monogrammatic crosses with alpha and omega (M. De Vogüé, *Syrie Centrale, Architecture civile et religieuse*, Paris 1865-77, p. 151). Vedi tav. XLVIII.