Floating above the river Sanzukawa (Japanese analogue to the River Styx) on her oar, Botan acts as the intermediary between the realm of mortals and the spirit world, and often brings knowledge from the latter to the former. In her hand we see a book which contains information about everyone in the mortal realm, although no one except Botan herself is allowed to read it. Behind her and the river we see the tall gates of King Enma's palace, a place containing knowledge of the kind one gets beyond death - particularly, as noted by the yin/yang symbol on the doors, knowledge beyond the constraints of duality.

Above her a crescent moon rides high in the sky, partially hidden by clouds, representing the deep feminine forces of the universe that can be glimpsed but are never fully revealed.

Meanings at a glance: Hidden mysteries, primal yin force, the quintessential mysterious woman. Divine/cosmic intent inherent in the underlying order of the universe. An unrevealed message.

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Ok, so Botan of "Yuu Yuu Hakusho" may not be the absolute pinnacle of everything the High Priestess represents...but she isn't too far off (affected bubbleheadedness aside), and the panoply that surrounds her was just too appropriate to pass up. ^_^

I played a little fast and loose with the design of King Enma's gates, since the only reference I could find in the anime without combing through hours and hours of footage only showed the top of it with its pretty, imposing roof.