दिवश्चैनमादित्याच्च दैवं मन आविशति ।तद्वै दैवं मनो येनानन्द्येव भवत्यथो न शोचति ॥१,५.१९ ॥
In plain words
From the sky and from the sun the divine mind enters into him. That is the divine mind by which a man becomes full of joy and does not grieve.
The commentators
Bṛhadāraṇyakopaniṣadbhāṣyam· bhāṣya
तथा दिवश्चैनमादित्याच्च दैवं मन आविशति— तच्च दैवं मनः, स्वभावनिर्मलत्वात् ; येन मनसा असौ आनन्द्येव भवति सुख्येव भवति ; अथो अपि न शोचति, शोकादिनिमित्तासंयोगात् ॥
In plain words
In that same way, the divine mind from heaven and from the sun enters him. That divine mind is naturally pure; through it, a man becomes joyful, as if happiness itself, and free from grief because he touches none of its causes.
Close to the Sanskrit
In the same way, the divine mind from heaven and from the sun enters him; and that divine mind, because of its natural purity, with which mind this one becomes joyful as it were, happy as it were; and moreover he does not grieve, due to the non-connection with causes of sorrow and the like.