Vyasadeva left a total of 108 upanisads with selected passages from the four Vedas, as well as other Vedic literature that speak directly about self-realization. The list also includes the Bhagavad-Gita, also called the Gitopanisad.

As expected, the Upanisads are full of interesting passages, but most of it is not easy to understand, be due to the scarcity of good translations or lack of explanations of what the passages mean.

Here is an interesting passage from the Bṛhad-āraṇyaka Upanisad (2.45), where Yājñavalkya teaches his wife Maitreyī about self-realization.

The context is that Yājñavalkya had two wives: Maitreyī and Kātyāyanī. The second was just interested in regular household affairs, while Maitreyī was interested in spiritual knowledge. When later in life Yājñavalkya was preparing to accept the Vanaprastha order and go to the forest, he called Maitreyī and proposed to make a settlement, dividing the properties between her and Kātyāyanī. To this, Maitreyī answered:

“My lord, if this whole earth, full of wealth belonged to me, tell me, would I be immortal by it, or not?”

Yājñavalkya replied: “No, your life would be the life of a rich person, but there is no hope of immortality by wealth.”

Then Maitreyī said “What use of it, if I will not become immortal? What you, my lord, know of immortality? Tell me clearly.”

Yājñavalkya said, “You are truly dear to me, and you have increased what is dear to me in you (spiritual knowledge). Therefore if you like, my lady, I will explain it to you. Please mark well what I say.”

“In reality, a husband is not dear; not because you love the husband, but because you love the Self (ātmā), the husband becomes dear. In reality, sons are not dear; not because you love the sons, but because you love the Self (ātmā), the sons become dear. In the same way, a wife is not dear; not because one loves the wife, but because he loves the Self (ātmā), the wife becomes dear.”

In this way, Yājñavalkya explained to Maitreyī how affection should be centered around the Lord, and not directly placed in the different objects of the senses. If a wife loves her husband and thinks that by her own power, she will make him love her, she will end up not being loved by the husband. Similarly, if one loves his children or his wife, and thinks that by his own power, he will make them love him, he will in the end not be loved by them. If however, he loves the Lord and from there loves the husband, children, and wife, seeing them in connection to the Lord, only then the Lord will make them love this devoted wife, husband, father, or mother.

The word “ātmā” (self) is commonly used to refer to the Lord in the scriptures. Sometimes ātmā is used in the sense of our personal self, being it the soul, or even the mind or body, according to the context, but the original meaning of the word ātmā is the Supreme Lord, the Supreme Self. The Lord should be our ultimate object of love, and by loving the Lord everyone will automatically love us.

Yājñavalkya then proceeds with his explanation, mentioning other things that are dear to ordinary people, such as wealth, cows, and other domestic animals, Brahmanas, Ksatriyas, the planets, the demigods, the Vedas, and the different living beings. The then concludes by saying that in reality, everything becomes dear only when one loves the Supreme Self, the Lord.

After explaining that ātmā, the Lord, should be the center of our affection, he continues by saying:

“Verily, the Self should be seen, heard, worshiped, and always meditated on. O Maitreyī, by seeing, hearing, worshiping, and understanding the Self (ātmā), everything becomes known.
Whoever looks for the brāhmaṇas elsewhere than in the Self, is abandoned by the brāhmaṇas.
Whoever looks for the kṣatriyas elsewhere than in the Self, is abandoned by the kṣatriyas.
Whoever looks for the worlds elsewhere than in the Self, is abandoned by the worlds.
Whoever looks for the devas elsewhere than in the Self, is abandoned by the devas.
Whoever looks for the living entities elsewhere than in the Self, is abandoned by the living entities.
Whoever looks for everything elsewhere than in the Self, is abandoned by everything.
These brāhmaṇas, kṣatriyas, worlds, devas, Vedas, all living entities, all and everything is the Self.”

The source of our material misery is that we look for satisfaction separately from Krsna. Everything that exists is connected with Krsna. As He explains in the Bhagavad-Gita (10.41-42): “Know that all opulent, beautiful, and glorious creations spring from but a spark of My splendor. But what need is there, Arjuna, for all this detailed knowledge? With a single fragment of Myself, I pervade and support this entire universe.”

Just like the light of the sun is just a faint reflection of the light of Krsna’s effulgence, all beauty, power, strength, intelligence, knowledge, and renunciation, or in other words, all the qualities that we find attractive in different beings and objects are just faint reflections of the opulence of Krsna. These different people and objects are just like mirrors, where the beauty, opulence, etc. of Krsna are reflected. However, due to the influence of illusion, we become attracted to the mirror, instead of becoming attracted to the person being reflected. When we become attracted by the illusion, instead of the real Self, we end up being abandoned by all these things, since this is the nature of the material illusion.

As Yājñavalkya proceeded in his explanation to Maitreyī:

“As the sounds of a drum being beaten cannot be captured by themselves, but the sound is seized when the drum or the beater of the drum is seized; or as the sounds of a conch being blown cannot be seized externally by themselves, but the sound is seized when the conch or the blower of the conch is seized, or yet as the sounds of a flute being played cannot be seized, but the sound is seized when the flute or the player of the flute is seized.”

It’s not possible to attain happiness by chasing people or material objects. Only when we connect ourselves with the Supreme Lord can all desirable things be attained.

“Just as clouds of smoke appear when we lit a fire using damp firewood, in the same way, O Maitreyī, the Rg Veda, Sāma Veda, Yajur Veda, Atharva Veda, Purāṇas, Itihāsas, Vidyās, Upaniṣads, ślokas, sūtras, vyākhyās, and anuvyākhyās, as well as everything that is sacrificed, food and drink, this world and other words and all creatures that exist come from the breath of the Supreme Person.”

This verse makes reference to Lord Maha-Vishnu creating all the universes and everything that exists through his exhalation. During the interval between his exhalation and his inhalation, all the universes become manifest, and the one hundred years of the life of Brahma go on, etc. When He inhales, all the universes are destroyed and all the souls merge into his body for a long period of rest until the next creation.