वेदानां सामवेदोऽस्मि देवानामस्मि वासवः।इन्द्रियाणां मनश्चास्मि भूतानामस्मि चेतना॥
vedānāṃ sāma-vedo ’smi devānām asmi vāsavaḥindriyāṇāṃ manaś cāsmi bhūtānām asmi cetanā
Word by word
The verse says
Among the Vedas I am the Sāma Veda. Among the gods, Indra. Among the senses I am the mind — and in living beings, I am consciousness.
In plain words
Three expected answers, and then the fourth.
The chief hymnal. The king of the gods. The mind, which rules the senses.
And then: consciousness in beings. Which is not the best of a category. It is the fact that there is anybody there at all.
Where you've felt this · in study
You are listing the features of a house to somebody — the number of rooms, the garden, the light in the mornings. Then you say: and it is the house my children grew up in. The first three are comparable with other houses. The fourth is not on the same scale and everybody knows it the moment it is said.
Going deeper
A list of superlatives quietly stops being a list of superlatives in the last word of this verse.
The Sāma Veda is the finest of the Vedas. Indra is the chief of the gods. The mind is the first among the senses. Each is a ranking inside a category. Then cetanā — consciousness in living beings — which does not rank anything. It names the condition without which none of the previous comparisons could have been made, or noticed, or cared about.
This is the same move as verse 20, made in miniature, and it will keep recurring.
For a reader it is a reminder of what the list is for. You can take each item as a fact about the world, in which case it is a long catalogue of other people's categories. Or you can notice that every few verses one of them points back at the reader, and that those are not accidents.