प्रजापतिर्लोकानभ्यतपत्तेषां तप्यमानानां रसान्प्रावृहदग्निं पृथिव्या वायुमन्तरिक्षातादित्यं दिवः ॥ ४.१७.१ ॥
In plain words
Prajāpati brooded upon the worlds; and from them, as he brooded, he drew out their essences: fire from the earth, the wind from the middle region, the sun from the sky.
The commentators
Chāndogyopaniṣadbhāṣyam
अत्र ब्रह्मणो मौनं विहितम् , तद्वेषे ब्रह्मत्वकर्मणि च अन्यान्त्यस्मिंश्च हौत्रादिकर्मरेषे व्याहृतिहोमः प्रायश्चित्तमिति तदर्थं व्याहृतयो विधातव्या इत्याह—
प्रजापतिः लोकानभ्यतपत् लोकानुद्दिश्य तत्र सारजिघृक्षया ध्यानलक्षणं तपश्चचार । तेषां तप्यमानानां लोकानां रसान् साररूपान्प्रावृहत् उद्धृतवान् जग्राहेत्यर्थः । कान् ? अग्निं रसं पृथिव्याः, वायुमन्तरिक्षात्, आदित्यं दिवः ॥
In plain words
Here the silence of the Brahma priest is prescribed. In that office, in the function of the priesthood, and in the remaining portions of the Hotṛ's and other sacrificial acts, the oblation of the Vyāhṛtis serves as an expiation. For that very purpose, the text declares that the Vyāhṛtis are to be ordained.
Prajāpati focused upon the worlds. Wishing to extract their innermost core, he engaged in deep meditative austerity. As those worlds felt the heat of his concentration, he drew forth their vital essences. What were they? Agni as the essence of the earth, Vāyu of the atmosphere, and Āditya of the heavens.
Close to the Sanskrit
Here silence of the Brahma priest is prescribed, and in that role and in the act of being a Brahma priest, and in other concluding parts of this, in the remainder of the Hotṛ's and other acts, the Vyāhṛti oblation is an expiation; thus, for that purpose the Vyāhṛtis are to be ordained, he says.
Prajāpati brooded upon the worlds—targeting the worlds with the desire to capture their essence there, he practiced austerity characterized by meditation. Of those worlds being heated, he extracted their essences, consisting of the vital core; he gathered them up, that is the meaning. Which ones? Agni as the essence of the earth, Vāyu of the atmosphere, Āditya of heaven.