तधैतद्ब्रह्मा प्रजापतयै उवाच प्रजापतिर्मनवे मनुः प्रजाभ्यः आचार्यकुलाद्वेदमधीत्य यथाविधानं गुरोः कर्मातिशेषेणाभिसमावृत्य कुटुम्बे शुचौ देशे स्वाध्यायमधीयानो धर्मिकान्विदधदात्मनि सर्वैन्द्रियाणि सम्प्रतिष्ठाप्याहिंसन्सर्व भूतान्यन्यत्र तीर्थेभ्यः स खल्वेवं वर्तयन्यावदायुषं ब्रह्मलोकमभिसम्पद्यते न च पुनरावर्तते न च पुनरावर्तते ॥ ८.१५.१ ॥
॥ इति पञ्चदशः खण्डः ॥
tadhaitadbrahmā prajāpatayai uvāca prajāpatirmanave manuḥ prajābhyaḥ ācāryakulādvedamadhītya yathāvidhānaṃ guroḥ karmātiśeṣeṇābhisamāvṛtya kuṭumbe śucau deśe svādhyāyamadhīyāno dharmikānvidadhadātmani sarvaindriyāṇi sampratiṣṭhāpyāhiṃsansarva bhūtānyanyatra tīrthebhyaḥ sa khalvevaṃ vartayanyāvadāyuṣaṃ brahmalokamabhisampadyate na ca punarāvartate na ca punarāvartate || 8.15.1 ||
|| iti pañcadaśaḥ khaṇḍaḥ ||
1. Brahmā taught this knowledge of the Self to Prajāpati, and Prajāpati taught it to Manu. Manu, in his turn, taught it to all human beings. A young man goes to live at his teacher’s house and serves him, and when he is free he studies the Vedas in the prescribed manner. After finishing all his studies, he goes back home and marries. But he continues to study the scriptures in a sacred place. He also teaches his children and disciples in such a way that they will be religious. He keeps all his senses under control and avoids violence unless he is at a holy place. This is how he lives his whole life. Then after death he goes to Brahmaloka, and he is not born again, he is not born again.
Tat ha etat, this [knowledge of the Self, which has so long been discussed]; brahmā prajāpataye uvāca, Brahmā taught Prajāpati [i.e., to Kaśyapa]; prajāpatiḥ manave, Prajāpati [taught] Manu; manuḥ prajābhyaḥ, Manu [taught] his own children [i.e., to all human beings]; yathā-vidhānam, strictly according to the prescribed rules; vedam adhītya, studying the Vedas; guroḥ karma atiśeṣena, in the time he is free after serving the teacher; abhisamāvṛtya ācāryakulāt, after returning home from the teacher’s house; kutumbe, he marries; śucau deṣe, in a holy place; svādhyāyam adhīyānaḥ, studying the scriptures regularly and as the occasion demands; dhārmikān vidadhāt, teaching his children and disciples to be truly religious; ātmani sarvendriyāṇi sampratiṣṭhāpya, withdrawing all organs into himself; ahiṃsan sarvabhūtāni, practising non-in-jury to all living beings; anyatra tīrthebhyaḥ, except at a holy place; saḥ khalu evam vartayan, he lives in this way; yāvat āyuṣam, to the end of his life; brahmalokam abhisampadyate, goes to Brahmaloka; na ca punaḥ āvartate na ca punaḥ āvartate, and he does not return, he does not return [to this world again]. Iti pañcadaśaḥ khaṇḍaḥ, here ends the fifteenth section. Iti chāndogya upaniṣadi aṣṭamaḥ adhyāyaḥ, here ends the eighth chapter of the Chāndogya Upaniṣad.
The Chāndogya Upaniṣad has altogether eight chapters, the first five of them being devoted to karma (worship), and the last three being almost exclusively devoted to ātmā-jñāna (Self-knowledge). One may ask, ‘Why waste so much space on worship?’ The answer is that worship is necessary in order to attain citta-śuddhi (purification of the mind).
A pure mind is like a clean mirror. If you stand before a clean mirror, you can see yourself clearly. Similarly, when your mind is purified, the Self reveals itself to you. You then know that your self is the Self of all and you are one with all.
The Upaniṣad says here that as soon as you receive the sacred thread, you go and live with your teacher as a brahmacārin. You become part of his family. You serve him in various ways, and he teaches you all that you need to know. Though you must work hard serving the teacher and also studying the scriptures, in the long run you learn more from the way your teacher lives. He shows you what kind of person you have to be.
If the teacher is satisfied with your progress, he permits you to go back home. This permission is called samāvartan—a convocation, in common parlance. You may or may not go back home. If you return home, you may marry and raise a family. The scriptures tell you what sort of life you have to live there. As a householder, you have many obligations to fulfil, and you fulfil them as best you can, following the scriptures.
There are two kinds of brahmacārins: The ṇaiṣṭhika brahmacārins never marry. They remain with the teacher and are life-long celibates. The upakurvāṇa brahmacārins live with the teacher for twelve years as celibates, and then they may return home and marry.
But no matter whether you remain with the teacher or you return home and become a householder, you are required to continue studying the scriptures. And you must study them according to the rules laid down about place and time. This is called svadhyāya.
Along with svadhyāya, you are also required to practise ahiṃsā, non-violence. The Upaniṣad says you must
ॐ आप्यायन्तु ममाङ्गानि वाक्प्राणश्च्क्षुः श्रोत्रमथो बलमिन्द्रियाणि च सर्वाणि । सर्वं ब्रह्मौपनिषदं माहं ब्रह्म निराकुर्यां मा मा ब्रह्म निराकरोदनिकारणमस्त्वनिकारणं मेऽस्तु । तदात्मनि निरते य उपनिषत्सु धर्मास्ते मयि सन्तु ते मयि सन्तु ॥
॥ इति अष्टमोऽध्यायः ॥
॥ ॐ शान्तिः शान्तिः शान्तिः ॥
॥ इति छान्दोग्योऽपनिषद् ॥
ॐ āpyāyantu mamāṅgāni vākprāṇaśckṣuḥ śrotramatho balamindriyāṇi ca sarvāṇi | sarvaṃ brahmaupaniṣadaṃ māhaṃ brahma nirākuryāṃ mā mā brahma nirākarodanikāraṇamastvanikāraṇaṃ me’stu | tadātmani nirate ya upaniṣatsu dharmāste mayi santu te mayi santu ||
|| iti aṣṭamo’dhyāyaḥ ||
|| ॐ śāntiḥ śāntiḥ śāntiḥ ||
|| iti chāndogyo’paniṣad ||