Maitrayaniya Upanishad 7.10.6

7.10.6

devatā savye vāme'kṣiṇyavasthitā iyamasyendrasya jāyā patnīti yojanā | uktañca bṛhadāraṇyake ‘indho ha vai nāma yo'yaṃ dakṣiṇe'kṣan puruṣastaṃ vā etamindham̐ santamindra ityācakṣate parokṣeṇa’ (a0 6) iti | ‘atha yadāme'kṣiṇi puruṣarūpameṣāsya patnī virāṭ’ (a0 6) iti ca | iyamanayorjāgradavasthoktā | svapnamāha, samāgama iti | hṛdayāntargate suṣau chidre nāḍījālasamāvṛte tayorindrendrāṇyoḥ samāgama ekasthāne'vasthānaṃ mithunībhāva ityarthaḥ | tayorantarhṛdayākāśe suptayostejastejanaṃ jīvanamannamiti yāvat, tadyallohitasya piṇḍaḥ pariṇāmastadubhayostayorannamityarthaḥ | tathā ca bṛhadāraṇyake ‘tayoreṣa saṃstāvo ya eṣo'ntarhṛdaya ākāśo'thainayoretadannaṃ ya eṣo'ntarhṛdaye lohitapiṇḍo'thainayoretat prāvaraṇaṃ yadetadantarhṛdaye jālakabhiva’ iti yadannaṃ pānañcopayujyate prāṇibhistadaudaryeṇāgninā pacyamānaṃ sthūlamadhyamāṇiṣṭhabhāgatāmāpadyate, tatra sthūlo bhāgaḥ puriṣamūtrādirūpo bahirgacchati, madhyamastu nāḍīdvārā sarvaṃ śarīraṃ rasalohitamāṃsādirūpeṇa pariṇamyā'nupraviśati, aṇiṣṭhastu manaādīnupacinoti | tatra yo madhyamo rasabhāgaḥ sa lohitapiṇḍa ityucyate tasya śarīrasthitihetutvāt, tayostadannamiti tātparyārthaḥ | idānīṃ tayoḥ sañcaraṇamārgamāha, hṛdayāditi |