One is stationery while the other on top is made to rotate by turning it with the help of a handle attached to it. The grain that is put into it gets crushed and the converted flour comes out. Thus the literal translation given above conveys that. Kabir cries out, is what makes the reader to contemplate on this Doha and realize for oneself the hidden meaning behind it. In this simile, Kabir establishes the natural phenomenon of dualities.
All nature is dual.
Day and night, life and death, joys and sorrows, thereby making life an ever changing process. Trapped in this duality, whatever we see is perishable. Nothing that we comprehend is eternal.