Canto 1 - Boyhood
Bāla-kāṇḍa
Chapter 18: The Advent of Rāma, Lakṣmaṇa, Bharata and Śatrughna
Text 1.18.12

कौसल्या शुशुभे तेन पुत्रेणामिततेजसा।
यथा वरेण देवानामदितिर्वज्रपाणिना॥

kausalyā śuśubhe tena putreṇāmita-tejasā
yathā
vareṇa devānām aditir vajra-pāṇinā

kausalyā = Kausalyā; śuśubhe = shone; tena = with her; putreṇa = son; amita-tejasā = of unlimited prowess; yathā = just as; vareṇa = with the best; devānām = of the devas; aditiḥ = Aditi shone; vajra-pāṇinā = Upendra Vāmana who had the signs of a thunderbolt in His hands.

Kausalyā shone with her son of unlimited prowess just as Aditi shone with the best of the devas, Upendra Vāmana, who had the signs of a thunderbolt in His hands.

Lord Rāma’s incarnation is not merely due to the fire sacrifice. It is also because of Kausalyā’s austerities. Kausalyā shone because her cherished desires were fulfilled by the Lord when He became her son who was of unlimited prowess. As stated in the Śruti, the Lord becomes excellent when He takes birth.[9] Now He exhibited His unbounded prowess due to His birth. The signs of a thunderbolt in Aditi’s son Upendra indicated that He is directly the Supreme Being. Amita-tejasā also indicates that Lord Rāmacandra is the illuminator of even Sūrya, the illuminator of the entire universe and the forefather of the dynasty into which He was born.

Yathā vareṇa devānām aditir vajra-pāṇinā can also indicate that Kausalyā shone with her son Rāma just as Aditi shone with Indra, the best of the devas and the holder of the thunderbolt. In this case, this comparison should be understood like the statement, iṣuvad gacchati savitā, “The sun moves like an arrow.”1

[9] sa u śreyān bhavati jāyamānaḥ.

1 Factually speaking, an arrow is insignificant in comparison to the sun, both in terms of size and speed. Nevertheless, such comparisons are made to indicate a partial similarity—the sun moves fast just as an arrow moves fast.