"The central icon at the portal of each of the three temples in the Group of the Cross specified the nature of the cosmic power and community responsibility that defined kingship for that temple.
At the portal of the Temple of the Cross, we see a variant of the World Tree. This cross-shaped Tree, with the Serpent Bar of kingship entwined in its branches and the Celestial Bird standing on its crown, was the central axis of the cosmos [the Milky Way galaxy].
Along this axis rose and descended the souls of the dead and the gods called from the Otherworld by the vision rite to talk to human beings. It was the path the Cosmic Monster took as the sun and Venus moved through its body on their daily journeys.
The king himself was the worldly manifestation of this axis, and this emphasized his role as the source of magical power. He was not only the primary practitioner of the rituals that contacted the Otherworld: he was the pathway itself.
In this portal the dead Pacal gives his son a scepter in the form of the monster that rests at the base of the World Tree--the same sun-marked monster that bore Pacal to Xibalba. Chan-Bahlum wields a disembodied head as an instrument of power, as had the Early Classic kings of Tikal and other kings before him."
Linda Schele and David Freidel, A Forest of Kings: The Untold Story of the ANcient Maya, p. 242-3