
A possible scenario for change in the significance of the motif may be from astronomical symbol to symbol of royal power then to symbol of seasonal change (i.e., the lion as symbol of summer, defeats the bull a symbol of winter).
The basic sense of the bull brought down by beasts of prey is an image of the fundamental forces of life and death in a terrible, intense struggle. As an image of the conflict that provides the sustenance of life, the lion and the bull are bound together as a single symbol.
If the bull is taken as the life-giving principle, the lion must be interpreted as the dynamic force that activates its release.
The Sumerians were the first to fix our zodiac in the heavens, and they assigned to Leo the house that the sun must traverse during the summer solstice. The bull, representing the principle of the sacrifice that gives life, is associated with spring, and so Taurus rules the house which the sun traverses in the vernal equinox, when the world returns to life.
In the symbolic language of Sumer, the lion is the great solar animal. Just as the light of the sun never varies, the lion exemplifies the clear light of awareness of eternity. The bull represents the lunar principle, which, waxing and waning in a constant cycle, exemplifies consciousness in the field of time. While the lion-consciousness is eternal and unchanging, the bull-consciousness, like the light of the moon, follows an eternal cycle of death and resurrection.