Ātma-tattva is the essence of all ātmās; the Supreme Self; knowledge or truth of Ultimate Reality.

The internal energy of Bhagavān has three aspects: existence (sandhinī), awareness (saṁvit) and bliss (hlādinī)

The sandhinī potency is the intrinsic power of existence of the Self-existent Bhagavān, and it upholds the existence of the individual ātmās and nature.

The saṁvit potency is the power of knowledge of Bhagavān by which He is all-knowing and which enables all others to know.

The hlādinī potency is the power of bliss, which bestows bliss both to Bhagavān — who is inherently full of bliss — and to others.

These three aspects of the internal potency are the very nature of Bhagavān and thus exist eternally in Him. The saṁvit potency includes and supersedes the sandhinī potency, and the hlādinī potency includes and supersedes the other two. This threefold internal energy of Bhagavān constitutes His very nature and that of His abode and associates.

Svayaṁ-jyoti means self-luminous. In other words, it describes something that illuminates itself and other things, just like a lamp illuminates itself and the objects around it.

Objects which produce no illumination (like a table, for example) require a light to shine on them before they can be perceived. But we do not need another lamp to see a lamp, it illuminates itself. It is “svayaṁ-jyoti.”

The term svayaṁ-jyoti specifies that sentience (jñāna – “knowledge, awareness”) is an attribute of ātmā. This is why ātmā can also be described as jñāna guṇaka (“an entity who possesses awareness”).

Learn more: The Ontology of the Jīva.

Consciousness (jñāna) as an attribute of ātmā is intrinsic and therefore eternal, but it can expand or contract in a real sense. The sentient knowledge of the self is not “destroyed,” it merely undergoes change in the form of expansion and contraction, by the influence of karma. The illusion of identifying oneself with a body needs a conscious base. Therefore, we see that self-illumination still exists in the ignorant ātmā – but to a contracted extent – as the basis for the experience of illusion.

Ātmā has two types of jñāna, namely svarūpa-bhūta and dharma-bhūta. The first is the intrinsic nature, i.e. the nature of being consciousness, the second is the quality of possessing awareness and knowledge.

The first one has no content in it except the sense of “I”. It is subjective consciousness. The second one is related to objects outside the self. It is objective awareness.

The conscious, self-illuminating nature of the ātmā (jñāna-svarūpa) is not lost. The nature of the ātmā is eternally to be full of brilliant consciousness. But the attribute of being able to use that luminous consciousness to illuminate objects (dharma-bhūta-jñāna) is covered. The attribute is covered and contracted, not the intrinsic nature which sprouts the attribute.

In summary, the ātmā inherently and eternally possesses the attribute of sentience, jñāna, and eternally possesses the constitution of consciousness. But the ability for these to shine can be expanded or contracted by the function of dharma-bhūta-jñāna.

Learn more: The Ontology of the Jīva.

Learn more: The Ontology of the Jīva.

In Sanskrit, the word "jñānam" is derived from the root √ jña avabodhane (to know) and has three etymological meanings:

1. Jñaptiḥ jñānam—knowing, awareness, consciousness, experience. Jñāna in this sense is without any content in it. It does not reveal anything except the subject itself. It is the intransitive usage of the word “jñāna” and can be translated as “contentless knowledge.”
2. Jñāyate anena iti jñānam—that by which something is known, or that which reveals something (artha-prakāśakaḥ). Jñāna in this sense has content. It has a subject to which it reveals and an object which is revealed by it. In Vedāntic terminology, it is called vṛtti-jñāna and can be translated as “content-filled knowledge.”
3. Jñānam asti asmin iti—that which knows or possesses knowledge, meaning a conscious being. In this sense, the word “jñāna” refers to the substratum or bearer of knowledge or awareness. In other words, it does not refer to knowledge in the first or second sense but to the bearer of the first and the subject to which the second is revealed. 

The second meaning is the most general meaning of the word jñāna. The function of knowledge, taken in this sense, is to reveal an object. It reveals an object to a conscious self, an ātmā, the bearer of knowledge signified by the third sense of “jñāna” discussed above.

Jñāna in the second sense of content-filled knowledge reveals itself as well as the object to a conscious self. It is thus described as svayaṁ-prakāśa, self-luminous. The self knows what is revealed to it by this knowledge. This knowledge, however, cannot know the object it reveals. That which knows but does not reveal the objects outside it except to itself is called pratyak or svasmai svayaṁ-prakāśa, self-luminous and self-conscious. This is the characteristic feature of the ātmā.

Learn more: What Is Jnana.

Śrīmad Bhāgavata 3.26.4

sa eṣa prakṛtiṁ sūkṣmāṁ
daivīṁ guṇamayīṁ vibhu
yadṛcchayaivopagatām
abhyapadyata līlayā

“Although he is very powerful, that ātma became attracted to the divine qualities of subtle prakṛti, and moved towards her. Prakṛti reciprocated by approaching the ātma, as was the will of the Lord.”

Vibhu (lit., all-pervading) is an adjective describing ātmā as an entity capable to pervade all types of bodies, as a result of being very subtle. Since the ātmā is especially “subtle”, he must be distinct from the body and mind. He is not born when the body he adopts is born, nor does he die when that body dies. Only the body takes birth and dies, not the ātmā .

Learn more: The Ontology of the Jīva.

Learn more: Are the Vedas Inherent in the Heart?.

Learn more: Interactions between the Ātmā and the Mind.

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