avyakta-cid-vyaktam adhārayad dhariḥ

avyakta-cid-vyaktam adhārayad dhariḥ

babhūva tenaiva sa vāmano vaṭuḥ

sampaśyator divya-gatir yathā naṭaḥ

The Lord, whose body is eternally endowed with ornaments and weapons and is invisible to the world and with spiritual form, became visible. Then, in the presence of his parents, to please them, the Lord, like an actor whose actions are hard to understand, became Vāmana, a brāhmaṇa-dwarf, a brahmacārī.

The Lord whose body appears with ornaments and weapons became visible. “Appears” is in the present tense to indicate that his body is eternal. That body, which is also invisible and has a spiritual svarūpa, became visible (adhārayat). He did not accept a form temporarily. He did this to please his parents. He did not do this by any material means. The Lord, like an actor with great powers of yoga, whose actions are hard to understand (divya), produces a body different from his original form, but does it so there is non-difference. In this way the Lord manifested a body which was spiritual.  

|| 8.18.13 ||

taṁ vaṭuṁ vāmanaṁ dṛṣṭvā

modamānā maharṣayaḥ

karmāṇi kārayām āsuḥ

puraskṛtya prajāpatim

The great sages, seeing the brahmacārī-dwarf Vāmana, joyfully putting Kaśyapa in front, had him perform the saṁskāras.

Karmāṇi refers to saṁskāras like hair cutting and giving the thread.

|| 8.18.14 ||

tasyopanīyamānasya

sāvitrīṁ savitābravīt

bṛhaspatir brahma-sūtraṁ

mekhalāṁ kaśyapo 'dadāt

At the sacred thread ceremony of Vāmanadeva, the sun-god uttered the Gāyatrī mantra, Bṛhaspati offered the sacred thread, and Kaśyapa offered a straw belt.

|| 8.18.15 ||

dadau kṛṣṇājinaṁ bhūmir

daṇḍaṁ somo vanaspatiḥ

kaupīnācchādanaṁ mātā