पुरुषो वाव यज्ञस्तस्य यानि चतुर्विंशति वर्षाणि तत्प्रातःसवनं चतुर्विंशत्यक्षरा गायत्री गायत्रं प्रातःसवनं तदस्य वसवोऽन्वायत्ताः प्राणा वाव वसव एते हीदंसर्वं वासयन्ति ॥ ३.१६.१ ॥
In plain words
A person is a sacrifice. His first twenty-four years are the morning pressing; the Gāyatrī has twenty-four syllables, and the morning pressing belongs to the Gāyatrī. Upon it the Vasus depend. The breaths are the Vasus, for they make all this abide.
The commentators
Chāndogyopaniṣadbhāṣyam
पुत्रायुष उपासनमुक्त जपश्च । अथेदानीमात्मन दीर्घजीवनायेदमुपासन जप च विदधदाह, जीवन्हि स्वय पुत्रादिफलेन युज्यते, नान्यथा । इत्यत आत्मान यज्ञ सपादयति पुरुष —
पुरुष जीवनविशिष्ट कार्यकारणसघात यथाप्रसिद्ध एव, वावशब्डोऽवधारणार्थ , पुरुष एव यज्ञ इत्यर्थ । तथा हि सामान्यै सपादयति यज्ञत्वम् । कथम् ? तस्य पुरुषस्य यानि चतुर्विशतिवर्षाण्यायुष , तत्प्रात सवन पुरुषाख्यस्य यज्ञस्य । केन सामान्येनेति, आह— चतुर्विशत्यक्षरा गायत्री छन्द , गायत्र गायत्रीछन्दस्क हि विधियज्ञस्य प्रात - तृतीयसवनमनुसतनुतेति माह प्राणाना५ रुद्राणा मध्ये यज्ञो विलोप्सीयेत्युद्धैव तत एत्यगदो ह भवति ॥ ४ ॥
In plain words
Meditation and recitation aimed at securing a son's life have already been explained. Now, prescribing this same meditation and recitation for one's own long life, the text declares: Only while living does a person attain the fruits starting with progeny, and not otherwise. Therefore, a person renders his very self a sacrifice.
The embodied human being formed of cause and effect is well known; the particle 'vā' serves to emphasize that the person alone is the sacrifice. This is how the text establishes the equivalence. How so? The first twenty-four years of a person's life correspond to the morning pressing of this human sacrifice. Through what common link? The text explains: the Gayatri meter has twenty-four syllables, and because the morning and third pressings share this metric essence, one sustains the ritual continuity. Fearing that the life-sacrifice might be cut short in the midst of the vital breaths and the Rudras, one pulls oneself up from that affliction, attains health, and becomes entirely free from disease.
Close to the Sanskrit
Meditation for the son's life and recitation have been spoken of. Now, prescribing this meditation and recitation for one's own long life, [the text] says: For a living person himself is joined with the fruit beginning with a son, not otherwise. Therefore a person accomplishes the self as a sacrifice—
The person as the aggregate of cause and effect qualified by life is just as well known; the word 'vā' is for ascertainment, meaning the person alone is the sacrifice. For thus it accomplishes sacrificeness through commonalities. How? Those twenty-four years of that person's life, that is the morning extraction of the sacrifice named after the person. By what commonality? It says: the Gayatri meter has twenty-four syllables, and having the Gayatri meter, carry out continuously the morning and third extraction of the prescribed sacrifice, it says. Lest the sacrifice among the vital breaths and the Rudras should be destroyed, pulling himself up right from there and attaining health, he indeed becomes free of disease.