Self enquiry is the prime means of Self knowledge. If you notice, there's only ‘I' and everything else is ‘this'. Scriptures refers the knowledge of ‘I' as para vidya and ‘this' as apara vidya or ‘Atma, anatma' viveka.
Atma, the inner presence is different from the body, senses, mind, intellect and the outside appearing world. It is pure without an association with anything else.
The Truth, Atman has no attributes, an ignorant, not knowing the true Self, mistakes Atman to be full of activities, gunas and emotions.
Every body goes through six variations birth, growth, modification, disease, decay and death, called (Shat vikaram). Atman is the witness of all drama, like an audience watching a play, unaffected by the situations happening in the play but due to ignorance we superimpose the formless atman with form, shape, size and color, sorrow and joy.
Atma is nithya, when a death occurs, the physical body merges with its source, five elements. The heat of the body merges with the element fire, the body bloats and the water oozes out to merge with the universal water, the matter with earth, the air with the outside air, limited space occupied by the body with the universal space, just like the space of a pot that breaks merges with the universal space.
The example given in this verse is that the space is not blue but appears blue to our limited vision, so too Atma appears to be acting and experiencing while Atma's presence alone activates everything. Not even a blade of grass can move in the absence of THAT Supreme presence. The entire universe would come to a standstill in its absence. The gist of this verse is that Atman is not the physical body.
Just like body's actions are superimposed on the immutable Atman, so also everything in the mind also superimposes in the Atman. This is due to ignorance of the true Self just like not knowing the rope, the snake is superimposed on the rope.
The atman, the supreme Consciousness is not involved with any activity. It's Akarta. The mind functions because it's is illumined by that supreme presence.
Due to ripples in the waterbody, the reflected moon appears to be broken, while the moon is totally undisturbed, so also, the Atman is undisturbed by the activities of all conditionings, upadhis. (body, senses, mind, intellect and the universe). This confirms that the mind is not Atman.
The question raised by the sincere seeker is ‘How can the atma be akartha, abogta?' Not the doer or the enjoyer?
Acharya Adi Sankara expounds the response in this verse.
Pleasure & pain, hunger & thirst, success & failure, victory & defeat, anger, fear, guilt, worry, love… all polarities are experienced in the waking state, when both body & mind are functioning and in dream state when the mind alone is active.
In deep sleep, the physical body, the senses, mind, intellect all dissolves in that One presence. Everyone rich, poor, king, beggar all experience the same peace in deep sleep. These thoughts, feelings, emotions are of the mind, not to the Atman.
Just like the Sun's presence alone activates the birds to chirp, the buds bloom, triggers beings to be active, but the Sun is not doing anything so also, the Atman's presence alone activates the BMI equipment to function and Atman is the witness. Again, this verse reiterates that Atman is the observer of the feelings and emotions of the mind.
Verse 24 emphasis that the Atma has no body, emotions, actions, likes & dislikes and this Atma is superimposed by anatma! Anything that's not Atma is Anathma!
(Adyaropam/Abhavadam). Not only the Truth is hidden but its also projected differently.
The seeker proposes the question, ‘How do I know atma? What's ITs lakshana? Personality?'
Atman is Sat- Chit-Ananda, Existence-Consciousness-Bliss.
‘Sat' -‘ Existence' here refers to always (Trikale), does not refer to Past, Present and Future but before Knowledge, when known and after gaining knowledge. For ex: When we snake is seen on a rope, the rope existed before the snake was seen, when known that it is not the snake and when realized it is the rope.
‘Chit' is jnanam… ‘Knowledge', The body is made of five elements so also every appearance. These 5 elements have no knowledge, they are inert, jadam. They don't know they exist where as you know you exist! How? Because you're that Satchidananda swaroopaha! Self illuminating Atman. You don't need a light or a pointer to know you exist!
All beings have knowledge at different proportions, ants, eagle, dogs, humans, but others don't know they exist except human beings.
‘Anandam' is endless Happiness, Bliss..It's not the pleasure or joy that's experienced due to the objects around which are polarity by nature. Atman is eternal Bliss, Niradisaya anandham.
Ex: Just like the characteristic of sugar is sweet, the essence of water is coolness, and the heat is of fire, brightness/luminosity are of the Sun, so also Atman is Eternity (sat, forever), Pure (nirmala, without any attributes), Consciousness, Bliss, is You!!
If you're in a pitch dark room or in a cave, you know you exist. How?
Atman is Satchitananda, the Sat swaroopa reflects in the pure intellect, which is referred to in Sanskrit as ‘Aabhasam'. This reflection creates the vibration in the mind/intellect equipment.
When we see an object, a vibration of that object is created in our mind. This vibration is ‘Vritti jnanam', buddhi vritti, like the waves in the waterbody. Both the vibration and the reflection are required to gain knowledge of anything that's seen.
An aviveki, ignorant (unable to differentiate the atman from anatman, Brahman from an appearance), says ‘I know', meaning, the reflection of the atman, is superimposed on the atman and referred to as ‘I know'. That ‘I' here is referred to ego, also called ‘aham kara vritti', not the Atman.
For ex: When the Suns rays, fall on a rock, it does not reflect the sun's rays, a water body reflects but the reflection is not very clear, whereas a clean mirror reflects the Sun clearly but even the mirror can reflect only when the light falls on it, doesn't do it automatically.
Acharya conveys in this verse that the intellect needs to be as clear as the mirror without any impurities, (Nirmalam) which are referred to as the desires, anger, jealousy, fear, guilt, worry for the Atman to reflect in it.
Every being is a combination of three gunas, Satva, rajas, tamas. Intellect is Satva, like a clear mirror, rajas is organs of action, (five karmendriyas), organs of perception, (five jnanendriyas), five air sheath, (five pranas), and tamas is the physical body.
We limit the atma by saying ‘I'm here', when Atma is all pervading, (Vibhuhu, Vishnu), ‘I'm afraid or angry' is an association with the mind, ‘I am hungry and thirsty' are with pranas, not of Atman. These feelings, thoughts are of the mind, while the eternal Satchitananda is Knowledge itself.
Atma has no dimensions or modifications, (Arupam, Avikari), whereas the intellect is inert, like a mirror that cannot reflect the Sun on its own without the presence of Sun.
Due to ignorance, not knowing the Self, the jivan sees the atman as the doer and refers ‘I am eating, I am doing', the ‘I' to Atman.
Such a jivan, ignorant (muhyan) sinks into samsara, the cycle of birth & death.
Atman never does anything (avikari) and intellect has no capacity to experience ‘I know'. But the individuality in us due to delusion, thinks of oneself as the seer and the knower.
Atman is the substratum of everything, the changeless behind all changes like the water in the waves of the ocean. Waves have no separate existence. Atman is not affected by the rise and fall of waves, by the changes caused in the arena of space and time.
Because of the illuminating Consciousness, there's an awareness of the various objects. Thoughts waves after waves of sorrow, dejection despair joy success failure anger passion, he who knows the knower of these waves is not affected.
When an individual sees the snake on the rope, immediately he is taken over by fear. Here the individual has superimposed the snake on the rope so also the anatman, the seen are superimposed on atman, referred as ‘parasapara adhyasam', interchanged.
The physical body experiences changes, ‘shat vikaram', six modifications- existence, birth, growth, disease, decay and death, while Atma is nithya, ever present. Not knowing the Self, there's a fear, I am sick, I suffer, I may die, I am useless. Limitations of the subject ‘I' is the fear.
The mind/intellect equipment is also inert, cannot function on its own just like even a clear mirror cannot reflect the Sun on its own, but Atman is Self illuminating. So long as the thought of separateness, identification with body exists, the misunderstanding exists. Know that I am not this limited being, I am paramartha, Self, supreme Self.
Once the seeker recognizes the real Self, even as mere theoretical knowledge, wakes up from own limitations and rediscovers himself to be the eternal bliss regains fearlessness.
Atma is One self illuminating Existence that illumines the body, senses, mind, intellect and the universe like lamp that illuminates all pots but pots cannot illuminate the lamp. So also, Atma cannot be understood by anathma, meaning atman is not not outside, go deeper within.
The very fact that we see objects, emphasizes that the Atman, seer IS behind as the substratum.
Ex: Like a street lamp is not affected by the wedding or funeral on the street, a mail person is not affected by the message that gets delivered so also Atman is not affected.
Acharya reiterates the exact verse 28 with a different example to emphasize the point.
However dark it maybe ‘I'm', nothing is required to know Self. IT is Self illuminating, (svayam prakashana), Knowledge, (jnana rupa), does not change, (nirvikara), Ever present, (nithyam), One Without a second (Ekam)!
Everything in this universe is visible due to the light from the lamp that shines on them. But to know that light, we don't need another lamp, that light is self illuminating. Similarly to know your presence you don't need another tool. Self illumines itself!
The seeker, ‘poorvapakshi' raises the question, ‘How do I know that atman?' This verse responds..The only way to get this Self knowledge (Atma bodham) is to negate those that are not atman, what's left is Atman alone.
When you make a tea, you filter to get drinkable tea, when you filter water to get clear water to remove impurities. You need to know what are impurities and what needs to be removed. So also remove all the non-atman and atman will self illuminate! ‘ Not this, not this' (‘Net neti ithi… ‘)
The only way is to study the scriptures with the help of a guru, who can explain the mahavakyas that proves that jivatman and paramatman (atman and brahman) are One and the same.