विकारो व्यवहारार्थो यथा तैजसपार्थिवाः ॥ १७ ॥
sa vai madhyaṁ ca tasya san
yaḥ — which (cause); tu — and; yasya — of which (product); ādiḥ — the beginning; antaḥ — the end; ca — and; saḥ — that; vai — indeed; madhyam — the middle; ca — and; tasya — of that product; san — being (real); vikāraḥ — the transformation; vyavahāra-arthaḥ — for ordinary purposes; yathā — as; taijasa — things produced from gold (which is itself derived from fire); pārthivāḥ — and things produced from earth.
Gold and earth are originally existing as ingredients. From gold one may fashion golden ornaments such as bracelets and earrings, and from earth one may fashion clay pots and saucers. The original ingredients gold and earth exist before the products made from them, and when the products are eventually destroyed, the original ingredients, gold and earth, will remain. Thus, since the ingredients are present in the beginning and at the end, they must also be present in the middle phase, taking the form of a particular product to which we assign for convenience a particular name, such as bracelet, earring, pot or saucer. We can therefore understand that since the ingredient cause exists before the creation of a product and after the product’s destruction, the same ingredient cause must be present during the manifest phase, supporting the product as the basis of its reality.
The Lord here explains that the original cause is certainly present in its effect, citing the example of gold and clay functioning as the causal ingredients of many different products in which gold and clay continue to be present. For our convenience, we assign different names to temporary products, although their essential nature continues to be that of the ingredient, and not of the temporary product.