Identification with this correct self must be realized to be free. For this, the complete knowledge of vedānta is necessary.

The term ātman exists because an ignorant individual sees themselves as a complex of body and mind in a world. However, these are expressions of the true self, caused by ignorance.

I am existence itself, shining as consciousness. And you are that too (tattvam apyasi). There is only one self. The self of everything and everyone is the one self, the only thing that is.

The self is that which is free (mokṣa) and stands alone (kaivalya). That which, as substrate and truth, is free from (and always bears witness to) gross, subtle, and causal bodies (sthūla, sūkṣma, kāraṇa śarīrā) and the world as a whole, and seemingly makes all phenomena possible (Vedānta explains how).

The self is beyond or prior to the five levels of experience (pañca kośāḥ), in the sense that it can seemingly manifest experience through and within itself. The self is the self-evident, unchanging, infinite, ever-present, ever-pure, silent witness (sākṣī) of the three states of experience (avasthā trayāḥ). That which is simply existence, consciousness, and fullness-bliss (sat cit ānanda).

Ātman or ātmā is equal to brahman. All its manifestations are called anātmā, not the self. Note: The relationship between ātmā and anātmā is non-dual, and therefore not an ordinary relationship, but an ontological relationship (satya mithyā). Forms appear to the self as objects dependent on it. This is what we call mithyā, false or dependently real, and therefore impermanent and changeable. Satya is the independent reality of this, also called consciousness (cit) or self.

Everything that is an-ātmā is therefore a-sat (not truly true and self-existent). Ātman is sat, full existence itself.

The material expression that is not self is therefore dependent on its substrate, pure consciousness, pure knowledge, self. Anātmā is therefore ātmā, but ātmā as an independent, infinitely radiant self is free from all objects of anātmā, non-self.

The term ātmā is necessary from the perspective of an ignorant living being (the jīva) to begin self-inquiry (ātma vicāra). So I can say, I exist naturally as consciousness. Consciousness itself is itself without any self and knows nothing of a self. Therefore, it is free. It is existence itself, shining as awareness.

The term ātman invites us to see brahman as ourselves. I-myself am as consciousness, the pure witness, the objectless subject of all objects. Because I exist, I must be the truth itself. The term exists to lift the individual living being from its cramped position to the truth. That is also why ātman is etymologically related (via Indo-European lines) to the Dutch "adem" (breath) and the German  "atem", from the Sanskrit root "an," meaning to breathe, to live.

For the wise, there is no self at all. They are simply full and free. The entire concept of self is an inert notion, invented to teach us, from our personal ignorance, that we are all that is, whether it seems to be happening or has already happened, whether it is manifested or not, the essence, the substance, the substrate is you, consciousness without qualities.

The self, therefore, is actually an invitation to view it in reverse. From your freedom to see the person as a humorous manifestation of your attribute-less self, simultaneously knowing that the appearance you first objectified is nothing other than this attribute-less self. For the wise, there is only full existence, in which everything seemingly unfolds, like a mirage in the desert air.

Everything, and therefore all people, seem numerous and varied, but are simply ātman, because the self is unchanging, omnipresent, and undivided consciousness. Always one and the same, just as gold is always the same in all golden objects, and both the vast ocean and the tiny wave, water.

The word ātman is sometimes also used in scriptures to mean "self," "I," or "specific mind" in the usual sense of I, the person. For example, in the word jīvātmā (the individual self, as experienced in ignorance by the living being, human being) or in ātma vinigraha (control of the individual mind). This must be distinguished, with the help of the teacher who explains the mantra or concept.

In this way, the word ātman emphasizes the fundamental human problem of adhyāsa, where you falsely believe yourself (ātman) to be something you are not: limited, mortal, defective, and in various respects inadequate. This is why mokṣa, freedom through a correct self-image, with jñāna, knowledge of the false ideas that appear to oneself, exists. Thus, Vedānta is the science of that which I have already proven to be.

The teacher can explain when the universal (samaṣṭi) self is meant, and when the individual (vyaṣṭi) self is meant.

Three kinds of meaning of ātmā are distinguished, of which only the first is true:

1. mukhātmā: The principal (mukha), the only, essential, true ātman, which is brahman, consciousness, existence, bliss.

2. mithyātmā, the false (mithyā), dependent self, the temporary sense of self during life, because mukhātmā seems to be identified with the body-mind complex.

3. gaunātmā: qualities (guṇāḥ) that are apparently superimposed on ātmā, and thus seem to belong to ātmā. These are all objects and attributes, since ātman is attributeless.

Finally, a Sanskrit technical note: Ātman is the root form (pratipādika) in Sanskrit, ātmā is the first (strong) case. Therefore, we often encounter ātmā in the scriptures.