Aṃśu (Angshu) literally means ray or glow of light. According to Ṛgveda (Rigveda), when a certain portion part or aṃśa of the sacrificial moon-plant or somlatā (somlata) is grounded, what we have is known as aṃśu. Therefore, aṃśu is that which flows from the moon— pra syandasvba soma biśbebhiraṁśubhiḥ.
The word aṃśu literally refers to the moon, the crescent and the stem of a moon-plant that is a special component of the sacred medicinal potion, Soma, prepared by Vedic experts. A mantra in the Ṛgveda says— “O Sabita! (that is, O Āditya!), Hiraṇyastūpa (Hiranyastupa) of Aṅgira lineage used to prepare this ghee-mixed rice and invoke you. In the same way, I, Arcana (Archana), his son, offer to you with this curd my salutations and pray that you protect us all. Just as those performing oblations by the fire remain scrupulous about the portions of moon-plants (aṃśa) or its stalks, I, too, am dedicated towards serving you” — eka tvārcannabase bandamānaḥ/ somasyebāṁśu pratijāgarāham.
- The meaning of the verbal root aś (ash) is to diffuse or to fill or to spread. Another mantra in Ṛgveda says— “Priests, after extracting the essence of the moon-plant, now dwell on the cow hide that was spread for extracting the moon” — aṃśuṃ duhanto adhyāsate dibi.
Yāskain his Nirukta has analysed this piece of mantra and defined the word aṃśu in the following way— aṃśuḥ śam aṣtamātro bhabati ananāya śaṁ bhabatīti ba—i.e., drinking aṃśu or soma grants (aṣtamātro) contentment, that is, aṃśu provides beatitude in life. Skanadsvāmī (Skandaswami), an annotator of the sixth century, while defining this mantra writes that the the word ‘śam’ (sham) added to the verbal root aś (when the root means ‘is spread’ or ‘is drunk’) along with the suffix –u, generates the word aṃśa. Skanadsvāmī further explains—
aṣṭa (aś + kta ) mātraḥ byāptamātrah pītamātraḥ/ śamo makāro’śermadhyamanuprabiṣto’nu svārībhutaḥ ukāraśca pratyayaḥ.
Aṃśu is one of the many solar deities (Āditya ), and if the suffix –u is omitted from the evolution of the word aṃśu, we get the form aṃśa, who is also an Āditya — the sun’s rays. Maitrāyaṇī Saṁhitā (Maitrayani Samhita) says that rays of the sun felicitates a rays of the moon— yathādityā (suryaraśmayaḥ) aṁśumāpyāyayanti.
- According to Purāṇas, Aṃśa or Aṁśu was one of the twelve Ādityas conceived by Dakṣa’s (Daksha) daughter Aditi from Kaśyapa Prajāpati’s (Kashyapa Prajapati). Some Purāṇas have used the name Aṃśa to identify him while others have used the name Aṃśu . However, although Aṃśa and Aṃśu have been identified as different entities in Purāṇas, both have been described as being one with the sun. The sun that rises in the month of Agrahāyaṇa (Aghrayana) according to Bhāgavatapurāṇa (Bhagavatapurana), and that which rises in the month of Caitra (Chaitra) according to the Brahmāṇḍapurāṇa (Brahmandapurana), is known as Aṃśu. This Aṃśu, who is one Ādityas, has been referred to as Aṃśumān (Angshuman) in Matsyapurāṇa (Matsyapurana).