"What do you see there?" "Not anything, sir." The father said: "My son,
that subtile essence which you do not perceive there, of that very
essence this great Nyagrodha tree exists. Believe it, my son. That which
is the subtile essence, in it all that exists has itself. It is the
True. It is the Self; and thou, O Svetaketu, art it."

Here we are clearly taught that the "self," or inmost reality of every
person and thing is the Eternal One, or Brahma, or God.

[Sidenote: Illustration from the Bhagavad Gîtâ.]

The same doctrine is taught in a more advanced form by the poem called
the "Bhagavad Gîtâ," the date of which is probably more than a thousand
years later than that of the Upanishad just quoted. In this poem,
Krishna, incarnate for the nonce as Arjuna's charioteer, reveals for a
special purpose his identity with Brahma, the Eternal All; and Arjuna,
when sufficiently instructed adores him thus:--

"O infinite Lord of Gods! the world's abode,
Thou undivided art, o'er all supreme.
Thou art the first of Gods, the ancient Sire,
The treasure-house supreme of all the worlds.
The Knowing and the Known, the highest seat.
From Thee the All has sprung, O boundless Form!
Varuna, Vayu, Agni, Yama thou,[6]
The Moon; the Sire and Grandsire too of men.

The Infinite in power, of boundless force,
The All thou dost embrace; the Thou art All."[7]