Verse 21

प्रसन्नं स्फारगाम्भीर्यमक्षुब्धमपराहतम् ।हृदयं समतामेति शान्तवात इवार्णवः

In plain words

Clear, of vast depth, unagitated, unassailed, the heart attains perfect evenness -- like the ocean when the wind has died down.