Just as a crystal that has something superimposed on it is not stained by poison and other objects, so the mind without superimposition is not stained by difficulties.

The metaphor of sphaṭika — crystal — is classic in advaita. Pure crystal reflects without staining; if red cloth is superimposed, it appears red but remains transparent. Adhyāsa — superimposition — is the vṛtti that colors the mind. Without it, kaṣṭa occurs as event but not as stain. The mind does not “stain” because it has no substance to stain; it is prabhā — luminosity — not padārtha — dense object. Poison (viṣa) and ādya — other objects — are kaṣṭa in their forms; the crystal does not reject them, it simply does not participate in them. Adhyāsa is the mechanism of avidyā: believing that the superimposed color belongs to the crystal, that kaṣṭa belongs to the mind, that suffering is inherent to being.