8.18

अव्यक्ताद् व्यक्तयः सर्वाः प्रभवन्त्यहरागमे ।
रात्र्यागमे प्रलीयन्ते तत्रैवाव्यक्तसंज्ञके ॥

avyaktād vyaktayaḥ sarvāḥ prabhavanty aharāgame
rātryāgame pralīyante tatraivāvyaktasaṃjñake

Kṛṣṇa (कृष्ण) continues. The day and the night of 8.17 now have a rhythm of coming forth and dissolving.

The verse

All manifestations come forth from the unmanifest when the day comes; when the night comes they dissolve, right there, into what is called the unmanifest.

नेपालीमा

दिन आउँदा सबै व्यक्त रूप अव्यक्तबाट निस्किन्छन्। रात आउँदा तिनीहरू त्यहीँ, अव्यक्त भनिनेमा, विलीन हुन्छन्।

Where it sits

The worlds that return, in 8.16, return on this clock. Day: they appear. Night: they go back into the unmanifest that has a name. 8.19 will say the host of beings is the same host, helpless in the round. 8.20 will then name a further unmanifest that does not perish with them.

Split: अव्यक्तात् + व्यक्तयः + सर्वाः + प्रभवन्ति + अहस्-आगमे + रात्रि-आगमे + प्रलीयन्ते + तत्र + एव + अव्यक्त-संज्ञके

avyaktāt + vyaktayaḥ + sarvāḥ + prabhavanti + ahas-āgame + rātri-āgame + pralīyante + tatra + eva + avyakta-saṃjñake

Sanskrit, in depth

The words

देवनागरीWordGrammarSense
अव्यक्तात्avyaktātablativefrom the unmanifest. a (अ) + vyakta (व्यक्त) "manifest."
व्यक्तयःvyaktayaḥnominative plural of vyakti (व्यक्ति)manifestations.
सर्वाःsarvāḥnominative plural feminineall. Agrees with vyaktayaḥ (व्यक्तयः).
प्रभवन्तिprabhavantipresent, 3rd pluralthey come forth. pra (प्र) + bhū (भू).
अहस्-आगमेahas-āgamelocativeat the coming of the day. āgama (आगम) "arrival."
रात्रि-आगमेrātri-āgamelocativeat the coming of the night.
प्रलीयन्तेpralīyantepresent, 3rd plural, middlethey dissolve. pra (प्र) + lī (ली).
तत्रtatraindeclinablethere.
एवevaindeclinablethat very.
अव्यक्त-संज्ञकेavyakta-saṃjñakelocativein what is called the unmanifest. saṃjñaka (संज्ञक) "named."

The phrases

avyaktāt vyaktayaḥ sarvāḥ prabhavanti ahaḥ-āgame (अव्यक्तात् व्यक्तयः सर्वाः प्रभवन्ति अहःआगमे) is the morning of that day. From the unmanifest, all manifestations come forth when the day arrives. avyaktāt (अव्यक्तात्) is the source, ablative.

rātryāgame pralīyante tatra eva avyaktasaṃjñake (रात्र्यागमे प्रलीयन्ते तत्र एव अव्यक्तसंज्ञके) is the night. At night's coming they dissolve, right there, into that which has the name "unmanifest." tatra eva (तत्र एव) means the place they return to is the same place they came from. The locative avyaktasaṃjñake (अव्यक्तसंज्ञके) is that place.

Sanskrit in this line

अहः + आगमे ahaḥ + āgame is recited aharāgame (अहरागमे). अः + आ aḥ + ā becomes ā (आ). The visarga is not kept, and it does not become r (र्), because the next sound is a vowel. रात्रि + आगमे rātri + āgame is rātryāgame (रात्र्यागमे), इ + आ i + ā becoming yā (या). Two arrivals, two sandhis, both in the locative of āgama (आगम).

Say it back

Where they come from at day, and where they go at night. If the night dissolves them into a second place, tatra eva (तत्र एव) was skipped.