स्वभावो यादृशो यस्य न जहाति कदाचन ।
अङ्गारः शतधौतेन मलिनत्वं न मुञ्चति ॥
svabhāvo yādṛśo yasya na jahāti kadācana |
aṅgāraḥ śata-dhautena malinatvaṁ na muñcati ||
(Unknown source; cited in Śabda-kalpa-druma)
“Whatever one’s svabhāva [may be], one can never give it up. Charcoal does not give up its blackness [even] by washing it a hundred times.”