In Hinduism, the term Vedanta is used to describe schools of thought or philosophy. The three major schools of Vedanta are Advaita, Vishishtadvaita, and Dvaita, and they are distinguished from one another with respect to how they view the relationship between the individual soul/Self (Atman) and the ultimate reality (Brahman):
There is much to say about how Hinduism, as it developed, and came into contact with monotheistic religions, gradually became a religion where Vishnu (or less commonly, Shiva or Shakti/Devi) is seen as the primary God, especially after the age of the Puranas (early centuries AD), and the influence of the Bhakti Movement. This development can be seen in the latter two schools above (Vishishtadvaita, Dvaita).
However, this article aims to argue the two following points:
The following quotations will come from the Ten Principal Upanishads, which long predate the Puranas, and are part of the Vedas. Because there are so many quotations, the following section will cover one quotation which establishes each of the following points of Advaita Vedanta:
Additional quotations for each point of doctrine will be listed in Appendices after each section.
While the teaching that Atman is Brahman is found by implication many times in the Upanishads, what follows is a direct statement of this point of Advaita Vedanta:
Mandukya Upanishad - Chapter 1
1 OM! This Imperishable Word is the whole of this visible universe. Its explanation is as follows: What has become, what is becoming, what will become - verily, all of this is OM. And what is beyond these three states of the world of time - that too, verily, is OM.
2 All this, verily, is Brahman. The Self is Brahman. This Self has four quarters.
6 This is the Lord of All; the Omniscient; the Indwelling Controller; the Source of All. This is the beginning and end of all beings.
The Self, when capitalized, refers to Atman, which is essentially the eternal soul. And, the above states that "The Self is Brahman" - "The Source of All" - "the beginning and ending of all beings".
For additional citations, see Appendix I - Atman is Brahman.
If Atman is equivalent to Brahman, it must likewise be eternal. The following states that it is "not born", "has not sprung from anything", and is "birthless, eternal, everlasting":
Katha Upanishad - Book 1, Chapter 2
16 This syllable Om is indeed Brahman. This syllable is the Highest. Whosoever knows this syllable obtains all that he desires.
17 This is the best support; this is the highest support. Whosoever knows this support is adored in the world of Brahma.
18 The knowing Self is not born; It does not die. It has not sprung from anything; nothing has sprung from It. Birthless, eternal, everlasting and ancient, It is not killed when the body is killed.
19 If the killer thinks he kills and if the killed man thinks he is killed, neither of these apprehends aright. The Self kills not, nor is It killed.
This passage is echoed very closely in the Bhagavad Gita:
Bhagavad Gita 2:17-25
17 Know That to be indestructible by which all this is pervaded. None can cause the destruction of This Immutable.
18 These bodies of the embodied Self, which is eternal, indestructible and immeasurable, are said to have an end. Therefore fight, O Arjuna.
19 He who deems It (the Self) a slayer, and he who thinks of It as slain - both are ignorant. For, the Self neither slays nor is slain.
20 It (the Self) is never born; It never dies; having come into being once, It never ceases to be. Unborn, eternal, abiding and primeval, It is not slain when the body is slain.
21 Whosoever knows It to be indestructible, eternal, unborn and inexhaustible, how can that man slay, O Arjuna, or cause to be slain?
22 Just as a man casts off worn-out clothes and puts on new ones, so also the embodied Self casts off worn-out bodies and enters others which are new.
23 Weapons do not cleave It (the Self), fire does not burn It, waters do not wet It, and wind does not dry It.
24 This Self cannot be cut, burnt, wetted, nor dried up. It is eternal, all-pervading, stable, immovable and ancient.
25 This (Self) is said to be unmanifested, unthinkable and unchangeable. Therefore, knowing This to be such, thou shouldst not grieve.
The above is even more forceful than the passage from the Katha Upanishad. The Self is "eternal, indestructible and immeasurable", it "is never born, it never dies", it is "unborn, eternal", "eternal, unborn", "eternal, all-pervading", and "unmanifested".
For additional citations, see Appendix II - Atman is Eternal and Uncaused.
This point of Advaita Vedanta can be seen in passages such as the following:
Brihadaranyaka Upanishad - Book 1, Chapter 4
8 This Self is dearer than a son, dearer than wealth, dearer than everything else, and is innermost. Should a person (holding the Self as dear) say to one calling anything else dearer than the Self, '(what you hold) dear will die' - he is certainly competent (to say so) - it will indeed come true. One should meditate upon the Self alone as dear. Of him who meditates upon the Self alone as dear, the dear ones are not mortal.
9 They say: Men think, 'Through the knowledge of Brahman we shall become all'. Well, what did that Brahman know by which It became all?
10 This (Self) was indeed Brahman in the beginning. It knew only Itself as, 'I am Brahman'. Therefore It became all. And whoever among the gods knew It also became That; and the same with sages and men. The sage Vamadeva, while realizing this (self) as That, knew, 'I was Manu, and the sun'. And to this day whoever in like manner knows It as, 'I am Brahman', becomes all this entire universe. Even the gods cannot prevail against him, for he becomes their self. While he who worships another god thinking, 'He is one, and I am another', does not know. He is like an animal to the gods.
Notice that "whoever in like manner knows (the Self) as, 'I am Brahman', becomes all this entire universe". Further, one who, in spite of this, "worships another god thinking, 'He is one, and I am another', does not know. He is like an animal to the gods".
For additional citations, see Appendix III - Moksha is Obtained by Recognizing that Atman is Brahman.
Moksha being unity with Brahman can be seen in passages like the following:
Prashna Upanishad - Chapter 5
5 As a snake sheds its dead skin the person is free from every kind of sin. The Aum represents the Sama mantras that lead the person to the Brahman's land, Who is superior to Hiranyagarbha, that dwells in the souls of all the living creatures' band. There he merges with the Supreme Being and feels he is everywhere and in everything.
The above describes the experience of one who attains Moksha - "he merges with the Supreme Being and feels he is everywhere and in everything".
For additional citations, see Appendix IV - Moksha is Experiential Unity with Brahman.
Having established that Hinduism's earliest sources do in fact teach the Non-Dualism of Advaita Vedanta, this section will offer a very simple critique.
The simple yet inescapable problem with Hinduism's Non-Dualism, and likely the driving force behind the later development of Dualistic or Qualified Non-Dualistic schools of Vedanta, is as follows:
The existence of Maya, and more broadly, the situation in which, for some reason, there are embodied beings needing to realize that Atman is Brahman in order to merge back into Brahman, makes no sense. Is Brahman tormenting itself? Did Brahman create confusion, and pain, in order to make itself realize that it is itself, in order to merge back into a truly single unit once again?
In Christianity, this type of problem does not exist, because the souls of beings are created by God, and distinct from Him. That is why there is suffering - we are not God. Once that is replaced with a Non-Dualistic view, like that of Hinduism, suffering becomes nonsensical, as ultimately, the ultimate reality would have to have created that suffering for itself.
Hinduism teaches that ultimate reality, Brahman, must be realized in spite of the obfuscation of Maya. This is fundamentally nonsensical, and terminates in the conclusion that Brahman created for itself a situation of confusion and suffering.
Chandogya Upanishad - Book 6
2.1: 'In the beginning, dear boy, this was Being alone, one only, without a second. Some say that, in the beginning, this was Non-being alone, one only, without a second. From that Non-being arose Being.'
8.7 'That Being which is this subtle essence (cause), even That all this world has for its self. That is the true. That is the Atman. That thou art, O Svetaketu.'
Chandogya Upanishad - Book 7, Chapter 3
1 Mind indeed is Atman. Mind indeed is the world. Mind indeed is Brahman. Worship the mind.
Chandogya Upanishad - Book 4, Chapter 14-15
3 'This', thus he acknowledged. 'Dear boy, they have told you about the regions only; but I shall tell you the object of your desire (i.e. Brahman). Just as water does not cling to the lotus-leaf, so also sin does not cling to him who knows Brahman thus'. 'Revered sir, please instruct me further'. (The teacher) said to him:
1 'This person who is seen in the eye, he is the Atman', said the teacher; 'this is the immortal, the fearless. This is Brahman. Hence, even if one sprinkles clarified butter or water into the eye, it goes away to the edges.'
Chandogya Upanishad - Book 8
7.4 Prajapati said to them, 'The person which is seen in the eye is the Atman'. He added, 'This is the immortal, the fearless. This is Brahman'. 'But, revered sir, he who is perceived in water and he who in a mirror, which of these is the Atman?' It is he himself that is perceived in all these', replied Prajapati.
8.3 They replied, 'Just as we are ourselves, revered sir, well adorned, well dressed and well groomed, even so are both these, revered sir, well adorned, well dressed and well groomed.' 'This is the Atman', said he, 'this is the immortal, the fearless. This is Brahman'. They both went away satisfied in their hearts.
10.1 Prajapati said, 'He who moves about in dreams, he is the Atman. He is the immortal, the fearless. He is Brahman'. Indra went away satisfied in his heart.
11.1 Prajapati said, 'He who is fully asleep, composed, serene and knows no dream, he is the Atman. He is the immortal, the fearless. He is Brahman'. Indra went away satisfied in his heart.
Chandogya Upanishad - Book 8, Chapter 14
1 Verily, what is called Ākāsha is the revealer of name and form. That within which they are, is Brahman, that is the immortal, that is the Atman.
Brihadaranyaka Upanishad - Book 1, Chapter 4
8 This Self is dearer than a son, dearer than wealth, dearer than everything else, and is innermost. Should a person (holding the Self as dear) say to one calling anything else dearer than the Self, '(what you hold) dear will die' - he is certainly competent (to say so) - it will indeed come true. One should meditate upon the Self alone as dear. Of him who meditates upon the Self alone as dear, the dear ones are not mortal.
9 They say: Men think, 'Through the knowledge of Brahman we shall become all'. Well, what did that Brahman know by which It became all?
10 This (Self) was indeed Brahman in the beginning. It knew only Itself as, 'I am Brahman'. Therefore It became all. And whoever among the gods knew It also became That; and the same with sages and men. The sage Vamadeva, while realizing this (self) as That, knew, 'I was Manu, and the sun'. And to this day whoever in like manner knows It as, 'I am Brahman', becomes all this entire universe. Even the gods cannot prevail against him, for he becomes their self. While he who worships another god thinking, 'He is one, and I am another', does not know. He is like an animal to the gods.
Aitareya Upanishad - Chapter 3
1 Who is He upon whom we meditate thinking: "This is the Self"? Which one is the Self? Is it He by whom one sees form, by whom one hears sound and by whom one tastes the sweet and the unsweet?
2 Is it the heart (intellect) and the mind? It is consciousness, lordship, knowledge, wisdom, retentive power of mind, sense knowledge, steadfastness, though, thoughtfulness, sorrow, memory, concepts, purpose, life, desire, longing: all these are but various names of Consciousness (Prajnanam).
3 He is Brahma, He is Indra, He is Prajapati; He is all these gods; He is the five great elements - earth, air, akasa, water, light; He is all these small creatures and the others which are mixed; He is the origin - those born of an egg, of a womb, of sweat and of a sprout; He is horses, cows, human beings, elephants - whatever breathes here, whether moving on legs or flying in the air or unmoving. All this is guided by Consciousness, is supported by Consciousness. The basis of the universe is Consciousness. Consciousness is Brahman (Prajnanam Brahma).
4 He, having realized oneness with Pure Consciousness, soared from this world and having obtained all desires in yonder heavenly world, became immortal - yea, became immortal.
Brihadaranyaka Upanishad - Book 2, Chapter 4
6 The Brāhmana ousts (slights) one who knows him as different from the Self. The Kshatriya ousts one who knows him as different from the Self. Worlds oust one who knows them as different from the Self. The gods oust one who knows them as different from the Self. Beings oust one who knows them as different from the Self. All ousts one who knows it as different from the Self. This Brāhmana, this Kshatriya, these worlds, these gods, these beings, and this all are this Self.
Brihadaranyaka Upanishad - Book 4, Chapter 5
7 The Brāhmana ousts (slights) one who knows him as different from the Self. The Kshatriya ousts one who knows him as different from the Self. Worlds oust one who knows them as different from the Self. The gods oust one who knows them as different from the Self. The Vedas oust one who knows them as different from the Self. Beings oust one who knows them as different from the Self. All ousts one who knows it as different from the Self. This Brāhmana, this Kshatriya, these worlds, these gods, these Vedas, these beings and these all - are this Self.
Brihadaranyaka Upanishad - Book 3, Chapter 4
1 Then Usata, the son of Chakra, asked him. 'Yajnavalkya', said he, 'explain to me the Brahman that is immediate and direct - the self that is within all.' 'This is your self that is within all'. 'Which is within all, Yajnavalkya?' 'That which breathes through the Prāna is your self that is within all. That which moves downwards through the Apana is your self that is within all. That which pervades through the Vyana is your self that is within all. That which goes out through the Udana is your self that is within all. This is your self that is within all.'
(This is repeated 2 more times afterwards with variation)
Brihadaranyaka Upanishad - Book 4, Chapter 4
17 That in which the five groups of five and the (subtle) ether are placed, that very Atman I regard as the immortal Brahman. Knowing (Brahman) I am immortal.
Consider the following two together as a unit:
Mundaka Upanishad - Book 2, Chapter 1
11 This immortal Brahman alone is before. Brahman is behind. Brahman is to the right and to the left. Brahman alone is spread above and below. This whole universe is the supreme Brahman alone.
Chandogya Upanishad - Book 7, Chapter 25
2 So now is the teaching through Atman. Atman alone is below. Atman is above. Atman is behind. Atman is in front. Atman is to the south. Atman is to the north. Atman alone is all this. Verily, he it is who sees thus, and understands thus, has pleasure in Atman, delight in Atman, union in Atman, joy in Atman. He becomes Self-sovereign; he becomes free to act as he wishes in all the worlds. But those who know otherwise than this are ruled by others and live in perishable worlds; they are not free to act as they wish in all the worlds.
Garuda Purana - Chapter 44
Brahman is shorn of body, organs of sense, mind, intellect, vital principle and egoism. It is shorn of elements, Tanmatras (subtle particles), the gunas (qualities), birth and decay. It is manifest of itself, devoid of a form, eternally blissful, without any beginning, eternal, purified, intelligent, undecaying, existent, blissful, without second and eternal. [The state of mental realization]. "I am Brahman, I exist in Brahman" is known as Samadhi (mental concentration). The soul is known as the charioteer, the body as the chariot and the organs of sense are known as the horses. The objects of sense are known by the latter. The soul is endued with mind and the organs of sense. Therefore the learned designate it as the enjoyer. He, who is endued with the discriminative knowledge of the external objects and mental perception, attains to the station of Brahman and is not born again.
Aitareya Upanishad - Chapter 1
1 In the beginning all this verily was Atman (Absolute Self) only, one and without a second. There was nothing else that winked. He (Atman) willed Himself: "Let Me now create the worlds".
Brihadaranyaka Upanishad - Book 1, Chapter 4
1 In the beginning, this (universe) was but the self (Viraj) of a human form.
10 This (self) was indeed Brahman in the beginning. It knew only Itself as, 'I am Brahman'. Therefore It became all.
Isha Upanishad - Chapter 1
6 The wise man beholds all beings in the Self, and the Self in all beings; for that reason he does not hate anyone.
7 To the seer, all things have verily become the Self: what delusion, what sorrow, can there be for him who beholds that oneness?
8 It is He who pervades all - He who is bright and bodiless, without scar or sinews, pure and by evil unpierced; who is the Seer, omniscient, transcendent and uncreated. He has duly allotted to the eternal World-Creators their respective duties.
Prashna Upanishad - Chapter 4
10 O Somya, the Self is untainted and colourless; It is pure and eternal, and has no form, big or small; One who knows this Supreme Self becomes united with It, He grows omniscient and is integrated with all.
Katha Upanishad - Book 1, Chapter 2
12 The wise man who, by means of concentration on the Self, realises that ancient, effulgent One, who is hard to be seen, unmanifest, hidden and who dwells in the buddhi and rests in the body - he, indeed, leaves joy and sorrow far behind.
13 The mortal who has heard this and comprehended it well, who has separated that Atman, the very soul of dharma, from all physical objects and has realised the subtle essence, rejoices because he has obtained that which is the cause of rejoicing. The Abode of Brahman, I believe, is open for Nachiketa.
Katha Upanishad - Book 1, Chapter 3
15 Having realised Atman, which is soundless, intangible, formless, undecaying and likewise tasteless, eternal and odourless; having realised That which is without beginning and end, beyond the Great and unchanging - one is freed from the jaws of death.
Katha Upanishad - Book 2, Chapter 2
12 There is one Supreme Ruler, the inmost Self of all beings, who makes His one form manifold. Eternal happiness belongs to the wise, who perceive Him within themselves - not to others.
13 There is One who is the eternal Reality among non-eternal objects, the one truly conscious Entity among conscious objects and who, though non-dual, fulfils the desires of many. Eternal peace belongs to the wise, who perceive Him within themselves - not to others.
Katha Upanishad - Book 2, Chapter 3
18 Having received this wisdom taught by the King of Death and the entire process of yoga, Nachiketa became free from impurities and death and attained Brahman. Thus it will be also with any other who knows, in this manner, the inmost Self.
Aitareya Upanishad - Chapter 3
1 Who is He upon whom we meditate thinking: "This is the Self"? Which one is the Self? Is it He by whom one sees form, by whom one hears sound and by whom one tastes the sweet and the unsweet?
2 Is it the heart (intellect) and the mind? It is consciousness, lordship, knowledge, wisdom, retentive power of mind, sense knowledge, steadfastness, though, thoughtfulness, sorrow, memory, concepts, purpose, life, desire, longing: all these are but various names of Consciousness (Prajnanam).
3 He is Brahma, He is Indra, He is Prajapati; He is all these gods; He is the five great elements - earth, air, akasa, water, light; He is all these small creatures and the others which are mixed; He is the origin - those born of an egg, of a womb, of sweat and of a sprout; He is horses, cows, human beings, elephants - whatever breathes here, whether moving on legs or flying in the air or unmoving. All this is guided by Consciousness, is supported by Consciousness. The basis of the universe is Consciousness. Consciousness is Brahman (Prajnanam Brahma).
4 He, having realized oneness with Pure Consciousness, soared from this world and having obtained all desires in yonder heavenly world, became immortal - yea, became immortal.
Brihadaranyaka Upanishad - Book 2, Chapter 5
1 This earth is (like) honey to all beings, and all beings are (like) honey to this earth. (The same with) the shining immortal being who is in this earth, and the shining, immortal, corporeal being in the body. (These four) are but this Self. This (Self-knowledge) is (the means of) immortality; this (underlying unity) is Brahman; this (knowledge of Brahman) is (the means of becoming) all.
(This is repeated 13 more times afterwards with minor variations)
Paingala Upanishad - Chapter 2
For Mahatmas (noble souls) to be always in (the conception of) 'I am Brahman' conduces to their salvation.
That which is equal in all is Brahman alone. One may attain the power to strike the ākāś with his fist; he may appease his hunger by eating husks (of grain), but never shall he attain emancipation who has not the self-cognition, 'I am Brahman'.
Brihadaranyaka Upanishad - Book 1, Chapter 4
8 This Self is dearer than a son, dearer than wealth, dearer than everything else, and is innermost. Should a person (holding the Self as dear) say to one calling anything else dearer than the Self, '(what you hold) dear will die' - he is certainly competent (to say so) - it will indeed come true. One should meditate upon the Self alone as dear. Of him who meditates upon the Self alone as dear, the dear ones are not mortal.
9 They say: Men think, 'Through the knowledge of Brahman we shall become all'. Well, what did that Brahman know by which It became all?
10 This (Self) was indeed Brahman in the beginning. It knew only Itself as, 'I am Brahman'. Therefore It became all. And whoever among the gods knew It also became That; and the same with sages and men. The sage Vamadeva, while realizing this (self) as That, knew, 'I was Manu, and the sun'. And to this day whoever in like manner knows It as, 'I am Brahman', becomes all this entire universe. Even the gods cannot prevail against him, for he becomes their self. While he who worships another god thinking, 'He is one, and I am another', does not know. He is like an animal to the gods.
Prashna Upanishad - Chapter 4
10 O Somya, the Self is untainted and colourless; It is pure and eternal, and has no form, big or small; One who knows this Supreme Self becomes united with It, He grows omniscient and is integrated with all.
Katha Upanishad - Book 2, Chapter 1
11 By the mind alone is Brahman to be realised; then one does not see in It any multiplicity whatsoever. He goes from death to death who sees multiplicity in It. This, verily, is That.
Chandogya Upanishad - Book 3, Chapter 14
1 Verily, all this universe is Brahman. From Him do all things originate, into Him do they dissolve and by Him are they sustained.
Brihadaranyaka Upanishad - Book 2, Chapter 4
12 As a lump of salt dropped into water dissolves with (its component) water, and no one is able to pick it up, but from wheresoever one takes it, it tastes salt, even so, my dear, this great, endless, infinite Reality is but Pure Intelligence. (The Self) comes out (as a separate entity) from these elements, and (this separateness) is destroyed with them. After attaining (this oneness) it has no more consciousness. This is what I say, my dear. So said Yajnavalkya.
13 Maitreyi said, 'Just here you have thrown me into confusion, sir - by saying that after attaining (oneness) the self has no more consciousness'. Yajnavalkya said, 'Certainly, I am not saying anything confusing, my dear; this is quite sufficient for knowledge, O Maitreyi'.
14 Because when there is duality, as it were, then one smells something, one sees something, one hears something, one speaks something, one thinks something, one knows something. (But) when to the knower of Brahman everything has become the self, then what should one smell and through what, what should one see and through what, what should one hear and through what, what should one speak and through what, what should one think and through what, what should one know and through what? Through what should one know That owing to which all this is known - through what, O Maitreyi, should one know the Knower?
(A variation of this passage is repeated in Book 4, Chapter 5, Verses 13-15)
Brihadaranyaka Upanishad - Book 4, Chapter 4
6 Regarding this there is the following pithy verse: 'Being attached he, together with the work, attains that result to which his subtle body or mind is attached. Exhausting the results of whatever work he did in this life, he returns from that world to this for (fresh) work'. Thus does the man who desires (transmigrate). But the man who does not desire (never transmigrates). Of him who is without desires, who is free from desires, the objects of whose desire have been attained, and to whom all objects of desire are but the Self - the organs do not depart. Being but Brahman, he is merged in Brahman.
7 Regarding this there is this pithy verse: 'When all the desires that dwell in his heart (mind) are gone, then he, having been mortal, becomes immortal, and attains Brahman in this very body'. Just as the lifeless Slough of a snake is cast off and lies in the ant-hill, so does this body lie. (Also see KaU 6.14) Then the self becomes disembodied and immortal, (becomes) the Prāna (Supreme Self), Brahman, the Light. 'I give you a thousand (cows), sir', said Janaka, Emperor of Videha.
Bhagavad Gita 2:72
72 O Arjuna! This is the state of the Self, the Supreme Spirit, to which if a man once attain, it shall never be taken from him. Even at the time of leaving the body, he will remain firmly enthroned there, and will become one with the Eternal.
Bhagavad Gita 5:24
24 One who is happy within, whose pleasure is within, and who has his light only within, that yogi, having become Brahman, attains absorption in Brahman.