Pound, grind and crush

Meaning

Pounding and grinding support the explanation of why the philosophers call their subject a stone. The matter begins as an earthly mineral and is later described as hard and dry enough to be crushed like a stone. This is one reason among others, not the whole definition: the paragraph goes on to a divided and reunited condition that endures fire and flows like wax. The verbs establish a material comparison; they should not be taken as a complete preparation method or proof of an independently identified mineral.