The death-date, as said above, is not a fixed one, like the birth-date. The date of the death is calculated by the relative positions of Sun and Moon at the spring equinox, varying with each year, and the death-date of each Solar Hero is found to be celebrated in this connection. The animal adopted as the symbol of the Hero is the sign of the Zodiac in which the Sun is at the vernal equinox of his age, and this varies with the precession of the equinoxes. Oannes of Assyria had the sign of Pisces, the Fish, and is thus figured. Mithra is in Taurus, and, therefore, rides on a Bull, and Osiris was worshipped as Osiris-Apis, or Serapis, the Bull. Merodach of Babylon was worshipped as a Bull, as was Astarte of Syria. When the Sun is in the sign of Aries, the Ram or Lamb, we have Osiris again as Ram, and so also Astarte, and Jupiter Ammon, and it is this same animal that became the symbol of Jesus--the Lamb of God. The use of the Lamb as His symbol, often leaning on a cross, is common in the sculptures of the catacombs. On this Williamson says: "In the course of time the Lamb was represented on the cross, but it was not until the sixth synod of Constantinople, held about the year 680, that it was ordained that instead of the ancient symbol, the figure of a _man_ fastened to a cross should be represented. This canon was confirmed by Pope Adrian I."[184] The very ancient Pisces is also assigned to Jesus, and He is thus pictured in the catacombs. The death and resurrection of the Solar Hero at or about the vernal equinox is as wide-spread as his birth at the winter solstice. Osiris was then slain by Typhon, and He is pictured on the circle of the horizon, with outstretched arms, as if crucified--a posture originally of benediction, not of suffering. The death of Tammuz was annually bewailed at the spring equinox in Babylonia and Syria, as were Adonis in Syria and Greece, and Attis in Phrygia, pictured "as a man fastened with a lamb at the foot."[185] Mithras' death was similarly celebrated in Persia, and that of Bacchus and Dionysius--one and the same--in Greece. In Mexico the same idea re-appears, as usual accompanied with the cross. In all these cases the mourning for the death is immediately followed by the rejoicing over the resurrection, and on this it is interesting to notice that the name of Easter has been traced to the virgin-mother of the slain Tammuz, Ishtar.[186] It is interesting also to notice that the fast preceding the death at the vernal equinox,--the modern Lent--is found in Mexico, Egypt, Persia, Babylon, Assyria, Asia Minor, in some cases definitely for forty days.[187]