This ceremony is traditionally performed while installing the first finished stone in the first course of the Temple structure. Since the Temple was already built, this ceremony was performed when the final piece (kalasam or dome) was to be set on top of the Shiva shrine (mandabam).
In relation to the human being, the dome corresponds to the human head. When a baby is born, there is a soft spot on the crown of the head. Even though, as an adult the spot has hardened, that same spot is still there. When Pratameshtika is performed it brings the “shakti” or power down through the body of the shrine, from whence it will flow back up through the body and rise up and out the crown or dome.
There is also a YouTube Video of the Pratameshtika Ceremony.
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