ŚVETĀŚVATARA UPANISHAD · 2.14

यथैव बिम्बं मृदयोपलिप्तं तेजोमयं भ्राजते तत् सुधान्तम् ।
तद् वात्मतत्त्वं प्रसमीक्ष्य देही एकः कृतार्थो भवते वीतशोकः ॥

yathaiva bimbaṃ mṛdayopaliptaṃ tejomayaṃ bhrājate tat sudhāntam ।
tad vātmatattvaṃ prasamīkṣya dehī ekaḥ kṛtārtho bhavate vītaśokaḥ ॥

As a metal disk (mirror), tarnished by dust, shines bright again after it has been cleaned, so is the one incarnate person satisfied and free from grief, after he has seen the real nature of the Self.

F. Max Müller · The Upanishads, Sacred Books of the East 15 (1884)