Seven was a mystical number among the ancients. The menorah, a sacred object as early as the time of Moses, had seven branches, as did many representations of the Tree of Life. Images of the menorah, the Torah shrine, and perhaps also the Temple were depicted frequently in catacomb frescoes and artefacts. Because the seven-branched lampstand continued to signify deliverance for early Christians, the image of the menorah has been found on occasion among the Christian motifs (see #178).
Representations of the cross also appear in the catacombs. The cross not only symbolized the four cardinal points of the universe from which came the life-giving winds and rains, but also was talismanic for many peoples. The crux gammata, or swastika, was adopted by eastern religions and depicted in pagan, Jewish, and Christian cemeteries; the crux commissa, shaped like the Greek letter tau, was pictured in Old Testament scenes of deliverance; the crux ansata, the Egyptian ankh, continued to be the sign for life in Coptic art. By the fourth century, the cross-like anchor and the trident, the Latin and Greek crosses, and the Christogram were all standard emblems of Christianity. In addition, the cross was a metaphor for the tree, which was related to the dying and saving God who was resurrected with the budding of its spring leaves.
Thus, both cosmic symbols—the menorah and the cross—had origins in the Tree of Life and signified the presence of a Lord who offered redemption and immortality.