All the primal shapes of a yantra are psychological symbols corresponding to inner states of human conciousness, through which control and expansion of psychic forces are possible ....
By constant reinforcement in ritual worship the apparently inert yantra-forms shake off their dormancy and act together as emblems of psychic power.
In this case, the yantra is said to move beyond 'form' and 'function' and emerges as a power diagram. "
From "Yantra" by Madhu Khana [Thames & Hudson]
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