One of the Gita's most vivid images. The Lord dwells in the heart of every being — not somewhere far away, not in a distant heaven, but right here, in the innermost region of every creature. And through Maya — His creative power — He sets all beings in motion, as though they were mounted on a revolving mechanism.
The 'yantra' image is striking. A potter's wheel turns because the potter's hands move it, but the clay on the wheel might imagine it is spinning on its own. Every living being carries the Divine within, and it is that presence which animates, sustains, and moves them through life. The body is the machine. The Lord is the one who turns it.
This is not meant to reduce living beings to puppets. It is meant to shift the center of gravity. When a person realizes that the real mover is within — that the Lord has been present in their heart all along — the search outside naturally comes to rest.