The use of symbols for conveying and enforcing truth goes back to earliest ages. God said to Noah, "I do set My bow in the cloud, and it shall be for a token of a covenant between Me and the earth." The ritual and appointments of the Tabernacle and its worship were an elaborate system of symbolism. So, also, we find the use of symbolism in Christianity. The need of appealing to the eye as well as to the ear, by visible signs for sacred truths, led the early Christians to employ a number of such symbols as an effective means of imparting instruction. But their use was not wholly a matter of choice. Anxious to seek and to support one another {52} under persecution, they were compelled to find some common signs of recognition which might be known only to themselves, and under which their new Faith might be safely concealed. _The Cross._--The Cross comes first in order. It is the especial emblem of Christianity. "It glitters on the crown of the monarch. It forms the ensign of nations. It crowns alike the loftiest spires of Christendom and the lowliest parish churches. It marks the resting-place of the departed who have died with faith in its efficacy, as it was the sign in Baptism of their admission to the kingdom of the Crucified." It is the symbol of Christ's atonement and of the salvation of men, and represents the Christian Faith, its demands and its triumphs. As might be expected, many fantastic stories were woven about this symbol in the middle ages. Yet back of their extravagance was often a true feeling. We see this even in the absurd legend of the tree from which our Saviour's cross was made. This legend was as follows: "for four hundred and thirty-two years after his expulsion from Paradise, Adam had tilled the ground in the valley of Hebron, when he felt his end approaching, and determined to send his son Seth to the gates of Paradise to demand from their keeper, 'the angel called {53} Cherubim,' the oil of mercy which had been promised to Adam when he was driven from the garden. Seth accordingly set forth, finding his way by the footprints of Adam and Eve, upon which no grass had grown since they passed from Paradise to Hebron. "The angel, after hearing the message, ordered Seth to look beyond the gate into the garden and to tell him what he saw. He beheld a place of inexpressible delight and beauty, with the four great rivers proceeding from a fountain in the center; and, rising from the edge of the fountain, an enormous tree, with wide-spreading branches, but without either bark or leaves. He was ordered to look a second time, when he saw a serpent twisted round the tree; and a third time, when the tree had raised itself to heaven, and bore on its summit a Child wrapped in glittering vestments.