a yantra is an instrument designed to curb the psychic forces by concentrating them on a pattern, and in such a way that this pattern becomes reproduced by the worshiper's visualizing power. It is a machine to stimulate inner visualizations, meditations, and experiences.
Zimmer provides the corpus's foundational definition of yantra as a psychic concentrating device with three functional registers: divine representation, inward devotional model, and dynamic chart for guided visionary transformation.
, Myths and Symbols in Indian Art and Civilization, 1946thesis