金光明最勝王經疏 3.161

3.161

贊曰：喻成本有。猶此等文，舊人或云：三身現常，或復當常。鎔銷練治，為顯金性本淨故。六度行於法為了因，除垢染故，得金體淨，非謂無金。

The commentary says: The metaphor establishes fundamental existence. Relying on such passages, earlier masters sometimes said: the three bodies are presently eternal, or alternatively, will be eternal. 'Smelted and refined' is in order to reveal that the nature of gold is fundamentally pure. The practice of the six pāramitās serves as an elucidating cause (vyañjakahetu) for phenomena: by removing defilement, one obtains the purity of the substance of gold; it does not mean there is no gold.