A comparative analysis of Śaṅkara's Advaita Vedānta and Thomas Aquinas's metaphysics, demonstrating the fundamental incompatibility between the Hindu doctrine of Brahman-Ātman identity and the Catholic doctrine of participation in divine being.
The attempt to reconcile Catholic theology with Advaita Vedānta—the project undertaken by Rama Coomaraswamy and other Perennialists—founders on a fundamental metaphysical incompatibility. While both traditions speak of "union with God" or "realization of Brahman," they mean radically different things. For Thomas Aquinas, the soul participates in God's being by grace while remaining really distinct from God. For Śaṅkara, the individual self (Ātman) is identical with Brahman, and the appearance of distinction is illusory.
This is not a superficial disagreement about terminology. It reflects fundamentally opposed metaphysical visions: Aquinas's universe is one of real creation from nothing, where creatures possess genuine (though dependent) existence and are ordered toward eternal communion with a personal God. Śaṅkara's universe is one of illusory superimposition, where the multiplicity of the world is māyā (neither real nor unreal), and liberation consists in realizing one's pre-existing identity with the impersonal Absolute.
This page presents extensive quotations from both Aquinas and Śaṅkara to demonstrate that their positions are not complementary perspectives on the same truth, but mutually exclusive metaphysical systems. The Perennialist project requires either fundamentally misreading one tradition or the other—or both.
For Aquinas, esse (existence, the act of being) is the most fundamental metaphysical principle. It is what makes every form and essence actual. In God alone, essence and existence are identical—God is Ipsum Esse Subsistens (Subsistent Being Itself). In all creatures, essence and existence are really distinct: a creature's essence does not include its existence, which must be received from God.
Summa Theologiae I, Q. 3, Art. 4: "Whether essence and existence are the same in God"
God is not only His own essence, as shown in the preceding article, but also His own existence. This may be shown in several ways. First, whatever a thing has besides its essence must be caused either by the constituent principles of that essence (like a property that necessarily accompanies the species—as the faculty of laughing is proper to a man—and is caused by the constituent principles of the species), or by some exterior agent—as heat is caused in water by fire. Therefore, if the existence of a thing differs from its essence, this existence must be caused either by some exterior agent or by its essential principles. Now it is impossible for a thing's existence to be caused by its essential principles, for nothing can be the sufficient cause of its own existence, if its existence is caused. Therefore that thing, whose existence differs from its essence, must have its existence caused by another. But this cannot be true of God; because we call God the first efficient cause. Therefore it is impossible that in God His existence should differ from His essence.
This distinction between essence and existence in creatures is the metaphysical foundation for the doctrine of creation. Because creatures do not possess existence by their own essence, they must receive it from God, who is existence itself.
Summa Theologiae I, Q. 4, Art. 2: "Whether God is the perfection of all perfections"
Existence is that which makes every form or nature actual; for goodness and humanity are spoken of as actual, only because they are spoken of as being. Therefore existence must be compared to essence, if the latter is a distinct reality, as actuality to potentiality. Therefore, since in God there is no potentiality, as shown above (I:3:1), it follows that in Him essence does not differ from existence. Therefore His essence is His existence.
For Śaṅkara, Sat (Being) is identical with Cit (Consciousness) and Ānanda (Bliss). Brahman is not "a being" or even "the supreme being," but pure, non-dual existence-consciousness. There is no real distinction between Brahman and anything else, because there is nothing else. The appearance of multiplicity is due to avidyā (ignorance) or māyā (illusion).
Brahma Sutra Bhashya I.1.4
Brahman is that from which the origin, subsistence, and dissolution of this world proceed... That omniscient, omnipotent cause from which proceed the origin, subsistence, and dissolution of this world—which world is differentiated by names and forms, contains many agents and enjoyers, is the abode of the fruits of actions, these fruits having their definite places, times, and causes, and the nature of whose arrangement cannot even be conceived by the mind—that cause, we say, is Brahman.
But Śaṅkara immediately qualifies this: the "origin, subsistence, and dissolution" of the world are not real transformations of Brahman, but appearances within the realm of ignorance. From the ultimate standpoint (pāramārthika satya), Brahman alone is real.
Vivekachudamani, Verse 20
A firm conviction of the mind to the effect that Brahman is real and the universe unreal, is designated as discrimination (Viveka) between the Real and the unreal.
For Aquinas, existence is received and participated. Creatures truly exist, but their existence is caused by and dependent upon God. For Śaṅkara, only Brahman truly exists. The apparent existence of individual things is illusory. This is not a difference of emphasis but a difference of kind.
The Catholic doctrine of creatio ex nihilo (creation from nothing) means that God freely wills to bring creatures into existence, not from any pre-existing material, but from absolute non-being. This is not a transformation of something that already exists, but the production of being itself.
Summa Theologiae I, Q. 45, Art. 1: "Whether to create is to make something from nothing"
To create is, properly speaking, to cause or produce the being of things. And as every agent produces its like, the principle of action can be considered from the effect of the action; for it must be fire that generates fire. And therefore to create belongs to God according to His being, that is, His essence, which is His existence. Now in God alone is His existence His essence. Hence to create is the proper act of God alone.
Creation is a real relation between God and creatures. The creature truly depends on God for its existence, but this dependence does not make the creature unreal. On the contrary, it is precisely because God is supremely real that He can cause other things to be real.
Summa Contra Gentiles II, Ch. 16: "That God Brought Things into Being from Nothing"
Everything that in any way exists is from God... Since, then, nothing can be added to the divine being, and since the divine being is being itself, it is impossible that anything should be made from a pre-existing subject, as from matter. Therefore, it must be that God brings things into being from nothing.
For Śaṅkara, the world is not created but superimposed (adhyāsa) on Brahman through ignorance. The classic analogy is the rope mistaken for a snake: the snake never truly exists, but appears to exist due to faulty perception. Similarly, the world appears to exist, but from the standpoint of ultimate truth, only Brahman exists.
Brahma Sutra Bhashya II.1.14
The world is not absolutely unreal like the son of a barren woman, nor is it absolutely real like Brahman. It has a dependent reality (vyāvahārika satya), valid only within the realm of ignorance. From the standpoint of ultimate truth (pāramārthika satya), Brahman alone is real, and the world is māyā—neither real nor unreal, but inexplicable.
The world has a kind of provisional reality (vyāvahārika satya) for those still under the sway of ignorance, but it has no ultimate reality (pāramārthika satya). When ignorance is dispelled, the world is seen never to have truly existed.
Vivekachudamani, Verse 227
The universe is verily Brahman – such is the august pronouncement of the Atharva Veda. Therefore this universe is nothing but Brahman, for that which is superimposed (on something) has no separate existence from its substratum.
Vivekachudamani, Verse 229
Whatever a deluded man perceives through mistake, is Brahman and Brahman alone: The silver is nothing but the mother-of-pearl. It is Brahman which is always considered as this universe, whereas that which is superimposed on the Brahman, viz. the universe, is merely a name.
For Aquinas, the world is truly real because it is truly created by God. For Śaṅkara, the world is ultimately unreal because it is superimposed on Brahman by ignorance. These positions cannot both be true. Either creatures have genuine existence (Aquinas) or they do not (Śaṅkara). The Perennialist attempt to treat these as complementary perspectives collapses under scrutiny.
For Aquinas, the soul is united to God by participation, not by identity. Participation means receiving a likeness of God's perfection while remaining really distinct from God. The soul participates in God's being by the very fact of existing, and participates in God's life by grace.
Summa Theologiae I, Q. 44, Art. 1: "Whether God is the efficient cause of all beings"
It must be said that every being in any way existing is from God. For whatever is found in anything by participation, must be caused in it by that to which it belongs essentially, as iron becomes ignited by fire. Now it has been shown above (I:3:4) when treating of the divine simplicity that God is the essentially self-subsisting Being; and also it was shown (I:11:3,4) that subsisting being must be one; as, if whiteness were self-subsisting, it would be one, since whiteness is multiplied by its recipients. Therefore all beings apart from God are not their own being, but are beings by participation. Therefore it must be that all things which are diversified by the diverse participation of being, so as to be more or less perfect, are caused by one First Being, Who possesses being most perfectly.
The analogy of iron becoming ignited by fire is crucial: the iron participates in the heat of the fire, but the iron does not become fire. It remains iron, now possessing a quality (heat) that it receives from the fire. Similarly, the soul participates in God's being and life, but does not become God.
This participation is perfected by grace, which elevates the soul to share in God's own life. But even in the beatific vision—the direct sight of God face to face—the soul remains a creature, distinct from God.
For Śaṅkara, the individual self (Ātman) is not merely like Brahman or united to Brahman—it is Brahman. The appearance of distinction is due to ignorance. The great Upanishadic saying "Tat Tvam Asi" (That Thou Art) declares the identity of Ātman and Brahman.
Chandogya Upanishad Commentary VI.8.7 (on "Tat Tvam Asi")
The sentence 'Tat tvam asi' (That thou art) is meant to remove the ignorance of the disciple concerning his own Self. The word 'tat' (that) refers to Brahman, the cause of the universe, and 'tvam' (thou) refers to the individual self. The sentence declares their identity. The apparent difference between Brahman and the individual self is due to limiting adjuncts (upādhis), just as the space in a pot appears different from universal space due to the pot. When the pot is destroyed, the space in the pot becomes one with universal space. Similarly, when ignorance is destroyed, the individual self is realized to be identical with Brahman.
Liberation (moksha) is not the attainment of something new, but the recognition of what has always been true. The self was never truly bound; it only appeared to be bound due to ignorance.
Brihadaranyaka Upanishad Commentary I.4.10 ("Aham Brahmāsmi")
This is the realization of the liberated sage. He does not become Brahman through any action or transformation, but realizes that he has always been Brahman. Bondage and liberation are both illusory from the standpoint of Brahman. The self was never bound; it only appeared to be bound due to ignorance (avidyā). Liberation (moksha) is not the attainment of something new, but the removal of ignorance that concealed one's true nature.
Vivekachudamani, Verse 6
Let people quote the Scriptures and sacrifice to the gods, let them perform rituals and worship the deities, but there is no Liberation without the realisation of one's identity with the Atman, no, not even in the lifetime of a hundred Brahmas put together.
For Aquinas, the soul participates in God but remains distinct. For Śaṅkara, the soul is identical with Brahman, and distinction is illusory. These are not two ways of saying the same thing. They are mutually exclusive metaphysical claims. The Perennialist who affirms both is either equivocating on the meaning of "union" or has failed to understand one (or both) traditions.
For Aquinas, we can know God in this life through analogical knowledge: we know God by analogy with creatures, recognizing both similarity and dissimilarity. We know that God is good, wise, and powerful, but we know these perfections exist in God in a mode infinitely surpassing our comprehension.
In the next life, the blessed see God face to face in the beatific vision. This is direct knowledge of God's essence, but it is a gift of grace, not a natural capacity of the human intellect. Even in the beatific vision, the soul remains a creature, and God remains infinitely beyond full comprehension.
For Śaṅkara, knowledge of Brahman is non-dual realization (jñāna). It is not knowledge of Brahman as an object, but the realization that the knower is Brahman. Subject and object collapse into non-dual consciousness.
Upadesasahasri (A Thousand Teachings) 11.7
I am other than name, form and action. My nature is ever free! I am Self, the supreme unconditioned Brahman. I am pure Awareness, always non-dual.
This realization is not mediated by grace or by any external agent. It is the removal of ignorance that reveals what has always been true. Works, rituals, and devotion may purify the mind, but they do not cause liberation. Only knowledge liberates.
Vivekachudamani, Verse 11
Work leads to purification of the mind, not to perception of the Reality. The realisation of Truth is brought about by discrimination and not in the least by ten million of acts.
Vivekachudamani, Verse 56
Neither by Yoga, nor by Sankhya, nor by work, nor by learning, but by the realisation of one's identity with Brahman is Liberation possible, and by no other means.
For Aquinas, knowledge of God is analogical and graced. For Śaṅkara, knowledge of Brahman is non-dual and self-authenticating. Aquinas's beatific vision preserves the distinction between knower and known; Śaṅkara's jñāna dissolves it. These are not complementary but contradictory accounts of ultimate knowledge.
For Aquinas, salvation is the beatific vision: the direct sight of God face to face, which is the fulfillment of all human longing. This vision is eternal communion with the Triune God, in which the soul participates in God's own life and happiness. The soul remains a creature, but is elevated by grace to share in divine life.
Crucially, salvation includes the resurrection of the body. The human person is not a soul trapped in a body, but a unity of body and soul. The body is good, created by God, and destined for glorification. The blessed will live forever as embodied persons in the new creation.
For Śaṅkara, liberation (moksha) is the realization of one's identity with Brahman. It is not the attainment of a new state, but the recognition of what has always been true. The liberated sage realizes "I am Brahman" (Aham Brahmāsmi) and is freed from the cycle of rebirth (samsāra).
Vivekachudamani, Verse 47
It is verily through the touch of Ignorance that thou who art the Supreme Self findest thyself under the bondage of the non-Self, whence alone proceeds the round of births and deaths. The fire of knowledge, kindled by the discrimination between these two, burns up the effects of Ignorance together with their root.
There is no resurrection of the body in Advaita Vedānta. The body is part of the illusory realm of māyā. Liberation is precisely escape from embodiment, not its glorification. The liberated sage has no further connection to the material world.
For Aquinas, salvation is eternal communion with God as an embodied person. For Śaṅkara, liberation is realization of identity with Brahman and escape from embodiment. These visions of ultimate fulfillment are not merely different—they are opposed. The Perennialist who affirms both has not achieved a higher synthesis, but has simply failed to notice the contradiction.
| Topic | Aquinas (Thomism) | Śaṅkara (Advaita Vedānta) |
|---|---|---|
| God/Brahman | Ipsum Esse Subsistens (Subsistent Being Itself); Personal God; Trinity of Persons | Sat-Cit-Ānanda (Being-Consciousness-Bliss); Impersonal Absolute; Non-dual (Advaita) |
| Essence vs. Existence | Really distinct in creatures; identical only in God | No real distinction; Brahman is pure existence (Sat) |
| Creation/World | Real production of being from nothing (ex nihilo); creatures have dependent but genuine existence | Superimposition (adhyāsa) of world on Brahman through ignorance; world is māyā (neither real nor unreal) |
| Soul's Relation to God | Participation in divine being by grace; soul remains really distinct from God | Identity (Ātman = Brahman); apparent distinction is illusory |
| Knowledge of God | Analogical knowledge through creatures; direct vision in beatific vision (by grace) | Non-dual realization (jñāna); removal of ignorance reveals pre-existing identity |
| Salvation/Liberation | Beatific vision: seeing God face to face; union by grace, not by nature | Moksha: realization of one's identity with Brahman; not attainment but recognition |
| Role of Works | Works done in grace merit eternal life; charity perfects nature | Works purify the mind but do not cause liberation; only knowledge (jñāna) liberates |
| Matter | Fully real, created good by God; principle of individuation | Less real than Brahman; product of māyā; obstacle to realization |
| Individuality | Eternally preserved; each person is unique and irreplaceable | Ultimately illusory; dissolved in realization of non-dual Brahman |
| Eschatology | Resurrection of the body; eternal life in communion with God | No resurrection; liberation is escape from cycle of rebirth (samsāra) |
| Ultimate Reality | God and creatures are both real; creatures depend on God but are not God | Only Brahman is ultimately real; multiplicity is illusory |
The Perennialist project—the attempt to reconcile Catholic theology with Advaita Vedānta—fails because it requires affirming contradictory metaphysical principles. One cannot coherently hold both that:
The Perennialist response is typically to claim that these are "different levels" of truth or "complementary perspectives." But this response fails to take seriously the claims of either tradition. Aquinas does not say that creation is true "on one level" but false "on a higher level." He says creation is true, full stop. Śaṅkara does not say that the world is real "from one perspective" and unreal "from another." He says the world is ultimately unreal, and the perception of its reality is due to ignorance.
The attempt to harmonize these traditions requires either:
None of these options is intellectually honest. The Perennialist project is not a higher synthesis but a confusion of categories. As with Neoplatonism, the attempt to assimilate Vedānta to Catholicism requires abandoning core Catholic doctrines. The Incarnation, the Trinity, the goodness of creation, the resurrection of the body—all of these are incompatible with Advaita Vedānta's non-dualism.
Rama Coomaraswamy's project, like that of his father Ananda and of Frithjof Schuon, requires choosing between Catholicism and Perennialism. One cannot serve two masters. The metaphysical gulf between Thomism and Vedānta is not a superficial disagreement about terminology, but a fundamental divide about the nature of reality itself.
See Also: