The sand mandala is a teaching aid disguised as an artwork. Monks work for days from memorised proportions, laying dyed sand through narrow metal funnels tapped with a rod, and what emerges is the floor plan of a deity's palace, exact to the grain. It is consecrated, used, and then — in front of everybody, usually while a Western audience visibly struggles — cut through with a vajra, swept into a heap, and poured into the nearest river so the blessing travels downstream. The destruction is not a lesson bolted on afterwards. It is the reason the thing was made.