At this time the faithful contented themselves with a mere suggestion of the sign, such as the combined X and P, the first two letters of the name of Christ in Greek, sometimes indicating the X with a transverse stroke across the P. Nothing more definite than this, and dating from primitive times, is to be found in the many inscriptions in the Roman Catacombs, where the Christians worshipped and buried their dead down at least to A.D. 260. In their private devotions, however, and in public also if occasion demanded an open profession of the faith, they early adopted the habit of making the sacred sign. They prayed, as is shown in the caricature just described, with arms spread crosswise, and amid the tortures of martyrdom, when the savage uproar drowned their voices or their failing strength denied them power to speak, their arms crossed above their heads bore their mute testimony to the steadfastness of their faith. "In every undertaking," writes Tertullian in the second century, "on coming in and going out, on dressing or washing, at the bringing of lights, on going to bed, in whatever occupation we are engaged, we imprint our foreheads with the sign of the Cross." To this testimony of the universal use of the practice in the primitive ages might be added that of many of the most eminent of the fathers, as, for instance, Lactantius, S. Athanasius, S. Basil, S. Ephrem, S. Cyril of Jerusalem, and his namesake of Alexandria, S. John Chrysostom, S. Ambrose, and S. Augustine of Hippo--all writers flourishing in the fourth century of our era. The growth of the use of the material cross was greatly accelerated by two important historical events, the conversion of the Emperor Constantine, with which we may put the claim of the Empress-mother, S. Helena, to have discovered the true Cross, and the outbreak of the Crusades. The story of the first of these events has been recorded for us by Eusebius, the friend and biographer of Constantine, as it was told to him by the Emperor himself; and the account is too well known to require repetition in detail here. It will be sufficient to recall the fact that in the year 312 A.D., as Constantine was marching against Maxentius, a vision of the Cross, with the legend "In this sign conquer," was vouchsafed to him, and that a dream subsequently instructed him to inscribe that symbol on the imperial banners. In obedience to this command a splendid banner was made, consisting of a cross-staff, from which, embroidered in jewels on a silken square, hung the sacred monogram; and under this standard, the _labarum_, the army marched to victory.