Maitri (Maitrāyaṇīya) Upaniṣad 7.10.p7

7.10.p7

7 cākṣuṣaḥ svapnacārī ca suptaḥ suptātparaśca yaḥ |
bhedāścaite'sya catvārastebhyasturyaṃ mahattaram ||

(7) He who sees with the eye, and he who moves in dreams,
He who is deep asleep, and he who is beyond the deep
sleeper—
These are a person's four distinct conditions.
Of these the fourth (_turya_) is greater [than the rest].
(8) In the three a quarter Brahma moves;
A three-quarter, in the last.
For the sake of experiencing the true and the false,
The Great Ātman (Soul, Self) has a dual nature!
—Yea, the Great Ātman has a dual nature!