Taittirīyopaniṣat 02.10 and 11

तस्माद्वा एतस्मात् मनोमयात्। अन्योऽन्तर आत्मा विज्ञानमयः। तेनैष पूर्णः। स वा एष पुरुषविध एव। तस्य पुरुषविधताम्। अन्वयं पुरुषविधः। तस्य श्रद्धैव शिरः। ऋतं दक्षिणः पक्षः। सत्यमुत्तरः पक्षः। योग आत्मा। महः पुच्छं प्रतिष्ठा ॥१०॥

tasmād vā etasmāt manomayāt। anyo'ntara ātmā vijñānamayaḥ। tena eṣaḥ pūrṇaḥ। sa vā eṣaḥ puruṣavidh eva। tasya puruṣavidhatām। anvayaṃ puruṣavidhaḥ। tasya śraddhaiva śiraḥ। ṛtaṃ dakṣiṇaḥ pakṣaḥ। satyam uttaraḥ pakṣaḥ। yoga ātmā। mahaḥ pucchaṃ pratiṣṭhā ॥10॥

[तस्मात् (tasmāt) - from that; वा (vā) - indeed; एतस्मात् (etasmāt) - from this; मनोमयात् (manomayāt) - from the mind-made; अन्यः (anyaḥ) - another; अन्तरः (antaraḥ) - inner; आत्मा (ātmā) - essence; विज्ञानमयः (vijñānamayaḥ) - consisting of knowledge; तेन (tena) - by that; एषः (eṣaḥ) - this; पूर्णः (pūrṇaḥ) - full; सः (saḥ) - he; वा (vā) - indeed; एषः (eṣaḥ) - this; पुरुषविधः (puruṣavidhaḥ) - of the nature of person; एव (eva) - indeed; तस्य (tasya) - of him; पुरुषविधताम् (puruṣavidhatām) - personhood; अन्वयम् (anvayam) - continuity; पुरुषविधः (puruṣavidhaḥ) - of the nature of person; तस्य (tasya) - of him; श्रद्धा (śraddhā) - honest interest; एव (eva) - indeed; शिरः (śiraḥ) - head; ऋतम् (ṛtam) - cosmic order; दक्षिणः (dakṣiṇaḥ) - right; पक्षः (pakṣaḥ) - wing; सत्यम् (satyam) - truth; उत्तरः (uttaraḥ) - left; पक्षः (pakṣaḥ) - wing; योगः (yogaḥ) - union; आत्मा (ātmā) - essence; महः (mahaḥ) - greatness; पुच्छम् (puccham) - tail; प्रतिष्ठा (pratiṣṭhā) - being established/installed;]

Therefore, beyond this mind-made (manomaya), there is another inner essence composed of knowledge (vijñānamayaḥ). By that, this is complete. He is truly of the nature of a person. His personhood is continuity. He is established having, honest interest (śraddhā) is the head, ṛta (the order) is the right wing, satyam (truth, reality) is the left wing, yoga is the essence, and greatness is the tail.

तदष्येष श्लोको भवति। विज्ञानं यज्ञं तनुते। कर्माणि तनुतेऽपि च। विज्ञानं देवाः सर्वे। ब्रह्म ज्येष्ठमुपासते। विज्ञानं ब्रह्म चेद्वेद। तस्माच्चेन्न प्रमाद्यति। शरीरे पाप्मनो हित्वा। सर्वान् कामान् समश्नुत इति। तस्यैष एव शारीर आत्मा। यः पूर्वस्य ॥११॥

tadaṣyeṣa śloko bhavati। vijñānaṃ yajñaṃ tanute। karmāṇi tanute'pi ca। vijñānaṃ devāḥ sarve। brahma jyeṣṭhamupāsate। vijñānaṃ brahma cedveda। tasmāccenna pramādyati। śarīre pāpmano hitvā। sarvān kāmān samaśnuta iti। tasyaaiṣa eva śārīra ātmā। yaḥ pūrvasya ॥11॥

[तत् (tat) - that; अस्य (asya) - of this; एषः (eṣaḥ) - this; श्लोकः (ślokaḥ) - verse; भवति (bhavati) - becomes; विज्ञानम् (vijñānam) - knowledge; यज्ञम् (yajñam) - sacrifice; तनुते (tanute) - extends; कर्माणि (karmāṇi) - actions; तनुते (tanute) - extends; अपि (api) - also; च (ca) - and; विज्ञानम् (vijñānam) - knowledge; देवाः (devāḥ) - gods; सर्वे (sarve) - all; ब्रह्म (brahma) - Brahman; ज्येष्ठम् (jyeṣṭham) - the eldest; उपासते (upāsate) - worship; विज्ञानम् (vijñānam) - knowledge; ब्रह्म (brahma) - Brahman; चेत् (cet) - if; वेद (veda) - knows; तस्मात् (tasmāt) - therefore; चेत् (cet) - if; न (na) - not; प्रमाद्यति (pramādyati) - becomes heedless; शरीरे (śarīre) - in the body; पाप्मनः (pāpmanaḥ) - of evil; हित्वा (hitvā) - having abandoned; सर्वान् (sarvān) - all; कामान् (kāmān) - desires; समश्नुत (samaśnuta) - attains equally; इति (iti) - thus; तस्य (tasya) - of him; एषः (eṣaḥ) - this; एव (eva) - indeed; शारीरः (śārīraḥ) - pertaining to the body; आत्मा (ātmā) - essence; यः (yaḥ) - who; पूर्वस्य (pūrvasya) - of the previous;]

Here is a verse about this: "Knowledge extends the sacrifice; it also extends actions. All the gods worship knowledge as the eldest Brahman. If one knows knowledge as Brahman and does not become heedless, having abandoned evil in the body, he attains all desires equally. This indeed is the bodily essence of him who was of the previous (one)."

Taittirīya Bhāshya 02.10 and 11

From the testimonial quoted, the following nuanced meanings come to light: 'śraddhā' - the honest interest, always upholds Vedas, i.e. knowledge; 'ṛtam' - is that order, which gives knowledge; 'satyam' - is the governing principle; 'yoga' - is the essence that allows all spheres to be experienced here, now; 'mahat' - the ego principle should become tail, i.e. left behind, when you come to 'vijñānamayaḥ' i.e. sphere of knowledge.

"... वासुदेवोऽन्तरस्ततः।

"... vāsudevo'ntarastataḥ।

[वासुदेवः (vāsudevaḥ) - Vāsudeva; अन्तरः (antaraḥ) - inner; ततः (tataḥ) - from that;]

"... From that, Vāsudeva is within.

श्रद्धाख्यं श्रुतिधर्तृत्वात् श्रद्धायां तच्छिरः स्थितम्स्मृ। ऋतं ज्ञानततेर्दाता चर्तस्थो दक्षिणः करः॥

śraddhākhyaṃ śrutidhartṛtvāt śraddhāyāṃ tacchiraḥ sthitamsmṛ. ṛtaṃ jñānataterdātā cartastho dakṣiṇaḥ karaḥ॥

[श्रद्धा (śraddhā) - "śraddhā"; आख्यं (ākhyaṃ) - named; श्रुति (śruti) - Veda; धर्तृत्वात् (dhartṛtvāt) - from the function of upholding; श्रद्धायां (śraddhāyāṃ) - in honest interest; तत् (tat) - that; शिरः (śiraḥ) - head; स्थितम् (sthitam) - situated; स्मृ (smṛ) - it is remembered; ऋतम् (ṛtam) - ṛtam; ज्ञानततेः (jñānatateḥ) - from the expanse of knowledge; दाता (dātā) - giver; च (ca) - and; अर्तस्थः (artasthaḥ) - situated in the hand; दक्षिणः (dakṣiṇaḥ) - right; करः (karaḥ) - hand;]

'śraddhā' - so named because it upholds the Veda, is regarded as the head in matters of host interest. The right hand, established in 'ṛtam', is considered the giver of knowledge.

वामः सत्यस्थितः सत्यं सतां यस्मान्नियामकः। योगाख्यं सर्वलोकस्य योगादत्रैव योगगम्। मध्यं पुच्छं महोनाम महनीयत्वतस्सदा॥"

vāmaḥ satyasthitaḥ satyaṃ satāṃ yasmānniyāmakaḥ। yogākhyaṃ sarvalokasya yogādatraiva yogagam। madhyaṃ pucchaṃ mahonāma mahanīyatvatassadā॥"

[वामः (vāmaḥ) - left; सत्यस्थितः (satyasthitaḥ) - established in truth; सत्यं (satyaṃ) - truth; सतां (satām) - of the reality, the good; यस्मात् (yasmāt) - from whom; नियामकः (niyāmakaḥ) - controller; योगाख्यं (yogākhyaṃ) - called yoga; सर्वलोकस्य (sarvalokasya) - of all worlds; योगात् (yogāt) - from yoga; अत्रैव (atraiva) - here itself; योगगम् (yogagam) - attained by yoga; मध्यम् (madhyam) - middle; पुच्छम् (puccham) - tail; महो नाम (maho nāma) - called great; महनियत् (mahanīyat) - greatness; वतस् (vatas) - due to; सदा (sadā) - always;]

Left hand, established in 'satya', from that, the truth, the good, and the reality is governed. Called 'yoga', as all the worlds are attained here, by yoga. The middle tail, called great (maho), as greatness is always in it."