Why is Sankaracharya accused as Pracchana Bauddha (crypto-buddhist) by many Vedantins?

Question

Let us see some of the accusations of vedantins

SANKARA’S ACCUSERS

Bhaskara (9th Century CE), the propounder of bhedabheda-siddhanta was one of the earliest Indian philosophers to attack Mayavada. In his commentary on Vedanta-sutra, Bhaskara does not mention Sankara by name, nor does he mention the name of his philosophy. However by reviewing his arguments against the monistic doctrine of maya and the Advaitic concept of anirvacaniya, it is obvious who and what he is alluding to.

Bhaskara is positively vitriolic when writing about the Advaitin’s concept of maya, referring to it’s adherents as bauddha-matavalambin (those that cling to Buddhist ideology) and goes on to say that their philosophy reeks of Buddhism (bauddha-gandhin). Bhaskara concludes that, “No one but a drunkard could hold such theories” and that Mayavada is subversive of all sastrika knowledge:

vigitam vicchinna-mulam mahayanika-bauddhagathitam mayavadam vyavarnayanto lokan vyamohayanti

Expanding on the contradictory and baseless philosophy of maya propagated by the Mahayanika Buddhists, the Mayavadis have misled the whole world. (Bhaskara’s Brahma-sutra-bhasya 1.4.25)

In his Siddha-traya, the Vaisnava philosopher Yamunacarya (917–1042 CE) stated that Buddhism and Mayavada was essentially the same thing. The only difference he could see was that while one was openly Buddhist (prakata-saugata), the other was simply covered (pracchana-saugata).

Following on from Yamunacarya, his disciple Sri Ramanuja (1017-1137 CE) also concurred that Mayavada was another form of Buddhism. In his Sri Bhashya commentary on the Vedanta-sutras, Ramanuja says that to claim that non-differentiated consciousness is real and all else is false is the same as the Buddhist concept of universal void. Furthermore, Ramanuja states that the concepts of such crypto-Buddhists make a mockery of the teachings of the Vedas (veda-vadacchadma pracchana-bauddha).

Another acarya in the line of Ramanuja, Vedanta Desika (1269–1370) wrote his famous Sata-dusini, a text expounding one hundred flaws found in Mayavada. In that work he refers to Sankara as a rahu-mimamsaka (one who obscures the true meaning of Vedanta), a bhrama-bhiksu (a confused beggar), a cadmavesa-dhari – one who is disguised in false garb, and goes on to assert that, “By memorizing the arguments of the Sata-dusini like a parrot, one would be victorious over the crypto-Buddhists.”

In another work, Paramata-bhangam, Vedanta Desika refers to Sankara as, “One who studied the Vedas in the shop of a Madhyamika Buddhist” (referring to Sankara’s param-guru Gaudapada of whom we will speak of later in this article).

Later philosophers also declared Mayavada to be crypto-Buddhism. The Sankhya philosopher Vijnana-bhiksu (1550–1600 CE) tried to reconcile Vedanta with Sankhya philosophy and synthesize all theistic schools of Indian thought into a philosophy that he called Avibhagadvaita (indistinguishable non-dualism). He was an impartial writer who analyzed both the merits and problems of the various doctrines that he encountered. Concerning Sankara’s philosophy, Vijnana-bhiksu states in his Sankhya Pravacana Bhasya:

brahma-mimamsayam kenapi sutrenavidya-matrato bandhasyanuktatat. avibhago vacanaditya-sutrair-brahma-mimamsaya abhipretas-yavibhaga-laksanadraitasy-avidyadivastavatve’pyavirodhaccha. yat tu vedanta-bruvanamadhunikasya mayavadas-yatra lingam drsyate tat tesamapi vijnanavadyeka-desitaya yuktameva.

There is not a single Brahma-sutra in which bondage is declared to be a mere deception. As to the novel theory of maya propounded by vedanta-bruva (those who claim to be Vedantists), it is only another type of Buddhist of the Vijnanavada school (vijnana-vadyekadesin). This theory has nothing to do with Vedanta and it should be understood that this doctrine of these new Buddhists, who assert the theory of maya and reduce our bondage to mere illusion is in this way refuted. (Sankhya Pravacana Bhasya 1.22)

Later on in his work, Vijnana-bhiksu also quotes the famous verse from Padma Purana (mayavadam asat-chastram). Vijnana-bhiksu considered Buddhism to be nastikavada, or atheism, as it was opposed to Vedic thought. Thus, in effect, he was declaring Mayavadis to be out and out atheists.

Amongst all acaryas and philosophers, Sri Madhvacarya was certainly the most hostile towards Sankara. Throughout his campaign to establish his philosophy of Dvaitavada, Madhva continuously attacked Mayavada, which he considered to be the worst kind of heresy. In his Anu-vyakhyana, Brhad-bhasya and Tattvodyota, Madhva also makes the claim that the Advaitins are crypto-Buddhists – na ca sunyavadinah sakasad vailaksanyam mayavadinah (there is no doctrinal difference between Buddhism and Mayavada). He even quotes Buddhist texts and compares them to Advaitin works to prove his point.

Reference

Answer 1

It is very natural that Vaishnavas do not like Sankara's interpretation of Vedanta. You can read my answer to another question here:

Did Shankara reject some doctrines of Atman or Brahman in order to reconcile Atman and Brahman?

Sankaracharya calls worshippers of forms as beginners and Brahman with form as not Its true essence. Naturally Sankara was called praccanna Bauddha by worshippers of forms of Brahman.

Answer 2

In his book The Advaita Tradition in Indian Philosophy: A Study of Advaita in Buddhism, Vedanta and Kashmira Shaivism, Prof. Chandradhar Sharma (formerly Professor of Philosophy Banaras Hindu University and then Chair of Philosophy at University of Jabalpur and Visiting Professor in the University of Allahabad) says on pages 34-35:

Many Vedic schools of Indian philosophy have noticed the similarities between Mahayana Buddhism and Advaita Vedanta. Eminent Advaitins like Gaudapada, Shriharsa and Chitsukha have pointed out the similarities between Mahayana and Vedanta. Gaudapada approves of the doctrine of ajativada and the critique of causation in Shunyavada and the arguments of Vijnanavada against realism (Gaudapada-karika IV, 5, 19, 22, 28, 72.). Shriharsa says that the onslaught of the dialectic of Shunyavada and Advaita Vedanta is valid against all views and cannot be set aside (Khandana-khanda-khadya, p. 61.). Chitsuka admits the similarity of the Madhyamika distinction between samvrti and paramartha with the Vedantic distinction between vyavahara and paramartha and defends the former against the attacks of Kumarila Bhatta (Tattva-pradipika, pp. 42-3.). Even Kumarila, who is an arch-opponent of Buddhism, admits that anatmavada is helpful for purification of mind and detachment. The theistic Vedantins, Bhaskara, Ramanuja, Madhva, etc., are unanimous in condemning the Advaitin as a crypto-Buddhist (prachchhanna-Bauddha) which shows that they admit the similarities between Mahayana and Advaita Vedanta.

The fact that Buddha carried on, according to his own realisation, the Upanisadic tradition of Absolutism and that Mahayana Buddhists developed it in the light of the teaching of their Founder, is undeniable. Can anyone say that Buddha who accepts the Absolutism of the Upanisads and Mahayana Buddhists who follow him and develop it are opposed to the Upanisadic tradition, because they reject the ultimate reality of the individual self, while the schools of Vaishesika and Nyaya which pay allegiance to the Vedas, but which have reduced the self to an eternal substance devoid of consciousness and bliss like a stone-slab have continued the Upanisadic tradition?

Thus we see that Buddha's teachings of pratityasamutpada, anatmavada, Nirvana, spiritual discipline and his silence on the avyakrta reveal him as a great teacher of absolutism who carried on the tradition of the Upanisadic seers...Hinayana schools of...due to an imperfect understanding of these teachings, forgot his absolutism and created a metaphysics of radical pluralism in the form of the theory of momentary elements in their Abhidharma treatises and commentaries thereon. They substituted the dogmatism of the eternalists by an equally strong dogmatism of momentary elements which culminates in nihilism...The contradictions on Hinyayana philosophy were pointed out by Mahayana schools of Madhyamika and early Vijnanavada who correctly interpreted the absolutism of the Founder [Buddha]. The germs of the important doctrines of Mahayana are scattered in the Pitakas themselves, especially in the Suttapitaka, where there are many passages containing the spiritual absolutism of Buddha.

Prof. Sharma goes int great detail in his book comparing the various aspects of Advaita and Mahayana to conclude that they are the same (as from the quote above). Those Vedantic commentators who compared Buddhism to nihilism were doing so on a limited understanding of the Hinayana school only and not on the Mahayana school. Tibetian Buddhist monks (who are followers of the Mahayana tradition) have also told me that there is no difference between Advaita and Mahayana. Buddha was a proponent of the Upanishads tradition. Rather than a calling Sankara a crypto-Buddhist, it is probably more logical to call Buddhists crypto-Advaitists.

Answer 3

All Vedanta schools must have Atman at the core of all sentient beings (Bhagavad Gita 2.17-30). If it does not, then it is not Vedanta. Regardless of whether it is Dvaita, Advaita, Visishtadvaita, Shuddhādvaita or Bhedabheda, all have Atman and Brahman.

Similarly, all Buddhist schools must have no Atman or Self in all phenomena, regardless of whether it is unconditioned phenomena (Nirvana) or conditioned phenomena. If it does not fulfill this, then it is not Buddhism. This is confirmed in the essay "Vedanta and Buddhism: A Comparative Study" by German indologist Professor Helmuth von Glasenapp. This essay includes a definition of Atman or Self, that is consistent with Bhagavad Gita 2.17-30. This applies to all Hinayana / Theravada, Mahayana and Vajrayana schools.

This topic of Atman is a fundamental irreconcilable difference between Advaita Vedanta and Buddhism.

By this definition, since Adi Shankaracharya preached Atman at the core of all beings, he could not have been a Buddhist, crypto or otherwise. This can be seen in his compositions: Atma Bodha, Vivekachudamani, Aparokshanubhuti, Tattva Bodha and his commentaries.

Also, since Mahayana Buddhists ultimately accept that there is no Atman in all phenomena, they could not be Advaitins, crypto or otherwise. Some Mahayana concepts may have been mistaken for Brahman or Atman. For example, the Eternal Buddha refers to the Dharmakāya, the Buddha's "Dharma Body" or his body of teachings, and not his Self or spiritual form. This originates from the Buddha's saying in the Vakkali Sutta that "he who sees Dharma, sees me; he who sees me, sees Dharma."

Despite this, it is likely that Advaita Vedanta and Mahayana Buddhism would have had some degree of influence on each other, but not to the point of becoming the same thing.

The conclusion here is that Adi Shankaracharya was not a crypto-Buddhist, because he did not reject Atman. Attacking Advaita Vedanta as being Buddhism, is a straw man fallacy (quoted below). Also seen in this comment by Swami Vishwananda - "Advaitists do not call themselves Mayavadis. Advaitists do not assert that Maya is superior to Brahman". "Mayavada" is yet another straw man argument.

A straw man is a common form of argument and is an informal fallacy based on giving the impression of refuting an opponent's argument, while actually refuting an argument that was not presented by that opponent. One who engages in this fallacy is said to be "attacking a straw man".

Answer 4

Why is Sankaracharya accused as Pracchana Bauddha (crypto-buddhist) by many Vedantins?

Irrespective of whether Buddhism (mAdhyamika and yogAcAra, specifically) is similar to or not similar to advaita-vedAnta, the above accusations will not hold water if it can be shown that the doctrine propounded by Adi Shankaracharya can be derived purely from the prasthAna traya – the Upanishads, the Bhagavad GIta and the BrahmasUtras.

In this context, the main objection of the non-advaitic vedAntins is towards the advaita teaching that the world is not real. It will be shown that this idea is present in the Upanishads and the Bhagavad Gita. Only a few examples will be taken in the interest of space and time.

Unreality of the world can be derived from Bhagavad Gita

The first chapter of the Bhagavad Gita, deals with Arjuna vishAda yoga. The real teaching of Bhagavad Gita begins with the 11th sloka of the 2nd chapter (sAmkhya yoga) with the upadesa of Sri Krishna paramAtma. Right at the beginning of the upadesa itself, in Sloka 2.16, Bhagawan Krishna presents the idea that the world is not real. So it is worthwhile looking at the summary of the Gita from the beginning till this point. (All references to Gita slokas and commentary of Shankara and translation by Swami Gambhirananda are from the Gita supersite website)

Chapter 1 and upto Chapter 2 Sloka 10 – Mostly Arjuna vishAda. Arjuna’s sorrow

Because Arjuna is sorrowful, it would make sense for Bhagavan Krishna to address the source of the sorrow.

Sloka 2.11 – The pandits do not grieve for those who are departed or not departed. You (Arjuna) should not grieve.

Sloka 2.12 – (Why should there be no grief?) Because you (Arjuna), me (Krishna) and others always existed and will always exist.

Sloka 2.13 – Rebirth is a state just like boyhood, youth, old age. (The Self is eternal. Therefore, there is no need to grieve over this matter of birth and death).

Sloka 2.14 – (If the Self is eternal, then what is non-eternal? Here, Bhagavan talks about what is non-eternal.) The contacts of the organs with their objects produce happiness and sorrow. One must bear them with the idea that they have a beginning and an end and are transient.

Sloka 2.15 – The person for whom these transient things like happiness and sorrow are the same, is fit for moksha. (Interesting thing is that Bhagavan has so far not spoken about any yogas like bhakti yoga, jnana yoga, karma yoga, he has barely started talking about the Self and here itself he has shown a path to moksha! This idea of remaining the same in happiness and sorrow, under praise and insult and other opposites, is reiterated at multiple places in the Gita.)

Sloka 2.16 – This is the sloka of interest here. In previous slokas Bhagavan has mentioned that the Self is eternal and that happiness and sorrow, heat and cold are non-eternal. Bhagavan, in this sloka, gives a big reason why one must bear happiness and sorrow – it is because whatever is transient or non-eternal is unreal.

nāsatō vidyatē bhāvō nābhāvō vidyatē sataḥ. ubhayōrapi dṛṣṭō.ntastvanayōstattvadarśibhiḥ৷৷2.16৷৷

na asataH vidyate bhAvaH – the asat has no bhAva (the unreal has no existence) na abhAvaH vidyate sataH – the sat has no abhAva (the real has no non-existence) But the nature of both these, indeed, has been realized by the seers of Truth. (tattva darsibhih)

Bhagavan has talked about what is non-eternal and what is eternal in the previous Slokas. In this Sloka, he is giving an additional reason why one must bear happiness and sorrow. It is because the happiness and sorrow, are unreal! They are considered unreal because they are transient (their impermanence is mentioned in previous slokas). Because they are unreal and do not have an existence, Bhagavan is asking Arjuna to bear the pairs of opposites. This Sloka is very significant because it equates whatever is transient to whatever is unreal. The world, being transient, is thus also unreal.

The second part of the sloka talks about the people who see tattva (or truth). The seers of truth (tattva) are those who can discriminate between the real (sat) and the unreal (asat). This is exactly what advaita teaches!

In the above sloka it is implied that the world, along with transient phenomena like happiness and sorrow are asat. What then is sat or reality? Bhagavan answers this in the next sloka.

avināśi tu tadviddhi yēna sarvamidaṅ tatam. vināśamavyayasyāsya na kaśicat kartumarhati৷৷2.17৷৷

2.17 But know That to be indestructible by which all this is pervaded. None can bring about the destruction of this Immutable.

Bhagavan mentions here that the Atman, being eternal (cannot be destroyed), is sat or reality. These slokas then, from 2.11-2.17, at the beginning of Krishna paramAtma’s upadesa, already contain one of the fundamental doctrines of advaita that only Atman (eternal) is real and the entire world (everything that is non-Atman and hence non-eternal) is unreal.

Unreality of the world can be derived from the ChhAndogya upanishad

ChhAndoya Upanishad 6.1, Sanskrit text and translations are from Wisdomlib website for chhandogya upanishad

Svetaketu has studied all the Vedas (presumably minus the Upanishads or he studied just the Karma kanda or may be he did not pay much attention or may be his teachers did not teach him or for whatever reason), and still does not know anything about brahman, so his father Uddalaka starts to teach him.

śvetaketo yannu somyedaṃ mahāmanā anūcānamānī stabdho'syuta tamādeśamaprākṣyaḥ yenāśrutaṃ śrutaṃ bhavatyamataṃ matamavijñātaṃ vijñātamiti kathaṃ nu bhagavaḥ sa ādeśo bhavatīti || 6.1.3 ||

3.‘—(Did you ask your teacher for) that teaching by which what is never heard becomes heard, what is never thought of becomes thought of, what is never known becomes known?’ [Śvetaketu asked,] ‘Sir, what is that teaching?’.

yathā somyaikena mṛtpiṇḍena sarvaṃ mṛnmayaṃ vijñātaṃ syādvācārambhaṇaṃ vikāro nāmadheyaṃ mṛttiketyeva satyam || 6.1.4 ||

4. O Somya, it is like this: By knowing a single lump of earth you know all objects made of earth. All changes are mere words, in name only. But earth is the reality.

yathā somyaikena lohamaṇinā sarvaṃ lohamayaṃ vijñātaṃ syādvācārambhaṇaṃ vikāro nāmadheyaṃ lohamityeva satyam || 6.1.5 ||

5. O Somya, it is like this: By knowing a single lump of gold you know all objects made of gold. All changes are mere words, in name only. But gold is the reality.

yathā somyikena nakhanikṛntanena sarvaṃ kārṣṇāyasaṃ vijñātaṃ syādvācārambhaṇaṃ vikāro nāmadheyaṃ kṛṣṇāyasamityeva satyamevaṃsomya sa ādeśo bhavatīti || 6.1.6 ||

6. O Somya, it is like this: By knowing a single nail-cutter you know all objects made of iron. All changes are mere words, in name only. But iron is the reality. O Somya, this is the teaching I spoke of.

This chapter of chhAndogya Upanishad, thus presents some of the most important ideas of vedAnta. The importance is known because of repetition of the same ideas multiple times. The Upanishad further goes on and mentions –

sadeva somyedamagra āsīdekamevādvitīyam | .........Somya, before this world was manifest there was only existence, one without a second. (6.2.1)

tadaikṣata bahu syāṃ prajāyeyeti.....That Existence decided: ‘I shall be many. I shall be born (6.2.3)

Thus the summary of the position of the Upanishad is as follows –

1. Just as lump of earth is the material cause all objects made from lump of earth, brahman is the material cause of the universe (one without a second).
2. However, even though brahman is the material cause, the Upanishad says that only the lump of the earth (brahman) is the reality. Thus, only brahman is real. All transformations of brahman are just figures of speech, meaning, they are just conventions (all changes are mere words). Since Upanishads mention at multiple other places that brahman is changeless, it must be the case that these transformations are unreal (this is also directly hinted by the Upanishad when it says that only the lump of earth etc are real). Hence, the world is just an apparent transformation of brahman and not a real transformation.
3. This doctrine is the vivarta vAda of advaita and it implies that the world is not real.
4. The Upanishad also implies that all transformations are unreal. Hence, only the changeless and eternal is real (it is the same as the logic of the Gita).

The culmination of this entire teaching is that all duality is unreal and jIva and brahman have no bheda. No wonder starting from 6.8.7, the Upanishad repeats “tat tvam asi” 9 times, showing that jIva is none other than brahman and showing the importance of this teaching.

Unreality of the world can be derived from the Brihadaranyaka Upanishad

Sanskrit text and Translations are from wisdomlib website for Brihadaranyaka Upanishad

1.4.10. brahma vā idamagra āsīt, tadātmānamevāvet, aham brahmāsmīti | tasmāttatsarvamabhavat; tadyo yo devānām pratyabubhyata sa eva tadabhavat, tathārṣīṇām, tathā manuṣyāṇām; taddhaitatpaśyannṛṣirvāmadevaḥ pratipede, aham manurabhavaṃ sūryaśceti | tadidamapyetarhi ya evaṃ veda, aham brahmāsmīti, sa idaṃ sarvam bhavati tasya ha na devāścanābhūtyā īśate, ātmā hyeṣāṃ sa bhavati; atha yo'nyāṃ devatāmupāste, anyo'sāvanyo'hamasmīti, na sa veda, yathā paśurevam sa devānām | ….

10. This (self) was indeed brahman in the beginning. It knew only itself as. ‘I am Brahmaṇ.’ Therefore It became all. And whoever among the gods knew It all became That; and the same with sages and so on. The sage Vāmadeva, while realising 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 (universe) Even the gods cannot prevail against him, for he becomes their self. While one who worships another god thinking, ‘He is one, and I am another,’ does not know. He is like an animal to the gods…

Here are some gems from Shankara’s most excellent commentary on this –

1. There is no such thing in the world that really assumes a different state through some cause and still is eternal. Similarly, if identity with all be due to the knowledge of Brahman, it cannot at the same time be eternal. And if it be transitory, it would be, as we have already said, like the result of an action. But if by identity with all you mean the cessation, through the knowledge of Brahman, of that idea of not being all which is due to ignorance, then it would be futile to understand by the term ‘Brahman’ a man who will be Brahman. Even before knowing Brahman, everybody, being Brahman, is really always identical with all, but ignorance superimposes on him the idea that he is not Brahman and not all, as a mother-of-pearl is mistaken for silver, or as the sky is imagined to be concave, or blue, or the like.

2. This knowledge has never been observed either directly to remove some characteristic of a thing or to create one. But everywhere it is seen to remove ignorance. Similarly here also let the idea of not being Brahman and not being all that is due to ignorance, be removed by the knowledge of Brahman, but it can neither create nor put a stop to a real entity.

The Upanishad says that by knowledge of oneself being brahman, one becomes everything. Shankara’s logic above is that knowledge is only seen to remove ignorance and it cannot create or stop a real entity. Thus, one doesn’t really “become everything” as such due to knowledge, but only that as a result of the knowledge of brahman, one loses that incorrect idea, due to ignorance, that one is not everything.

For example, it is impossible for Karna to become the son of Surya, if he was not really the son of Surya. Karna was always the son of Surya, whether he knew it or not. Thus, knowledge of Karna as the son of Surya, is only removing Karna’s ignorance on the matter and it does not produce something which is not already there. No amount of knowledge can, for example, make Duryodhana as the son of Surya.

Thus, when the Upanishad says that it is knowledge of brahman which leads to identity with everything, it implies that knowledge only removes the current state of ignorance which is currently making us to believe in the duality of the world (and the duality between brahman and oneself). Thus, the current duality of the world, is not real.

The non-duality (not only in the future, but also in the present) is confirmed by the Upanishad when it says - While one who worships another god thinking, ‘He is one, and I am another,’ does not know. He is like an animal to the gods.

That the world of duality is transient (and hence unreal, by the logic of ChhAndogya Upanishad and the Bhagavad Gita) is also mentioned at other places in the Brihadaranyaka upanishad (notably 2.4.14) –

yatra hi dvaitamiva bhavati taditara itaraṃ jighrati, taditara itaraṃ paśyati, taditara itaram śrṇoti, taditara itaramabhivadati, taditara itaram manute, taditara itaraṃ vijānāti; yatra vā asya sarvamātmāivābhūttatkena kaṃ jighret, tatkena kaṃ paśyet, tatkena kaṃ śṛṇuyat, tatkena kamabhivadet, tatkena kaṃ manvīta, tatkena kaṃ vijānīyāt? yenedam sarvaṃ vijānāti, taṃ kena vijānīyāt? vijñātāram are kena vijānīyāditi || 14 ||

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 Maitreyī, should one know the Knower?

Unreality of the world can be derived from the taittirIya upanishad

TaittirIya upanishad defines brahman as – satyam, jnAnam, anantam brahma (2.1.1) Shankara mentions that these words, when they are taken together, seek to define brahman. These three words, serve to distinguish brahman from everything else, because a definition should distinguish something from everything else.

Here, we will confine ourselves to Satyam. What is Satyam? That which does not change (Bhagavad Gita and ChhAndogya Upanishad logic) is Satyam. Why should this be the case? In normal usage, we think the world is real, so we think that a pot that exists, for example, is real. The existence of the pot being true. But if brahman is Satyam in the same sense as a worldly pot, then Satyam jnAnam anantam brahma does not give us any distinguishing knowledge or definition of brahman. Hence brahman is Satyam is not in the same sense as a pot is Satyam. Brahman is Satyam in the sense that brahman does not change (it is never contradicted and is true in all periods of time). Whatever changes (the world) is then not real (not satyam).

Unreality of the world from other upanishads

Aitareya upanishad 1.3.12

tasya traya avasathAH trayaH svapnAH

This refers to the three states of Atman (jAgrut, svapna, sushupti or waking, dream and deep sleep) and equates all the three states to dreams. Thus indicating that the world is unreal.

Katha Upanishad 2.1.10-11

yadeveha tadamutra yadamutra tadanviha . mṛtyoḥ sa mṛtyumāpnoti ya iha nāneva paśyati .. 10..

manasaivedamāptavyaṃ neha nānā'sti kiṃcana . mṛtyoḥ sa mṛtyuṃ gacchati ya iha nāneva paśyati .. 11..

There is no difference here. Whoever sees difference here goes from death to death. The saying, which is already repeated twice is also mentioned in Brihadaranyaka upanishad 4.4.19 –

manasaivānudraṣṭavyaṃ, neha nānāsti kiṃcana | mṛtyoḥ sa mṛtyumāpnoti ya iha nāneva paśyati || 19 ||

It shows the importance of this teaching that denies all differences. The denial of differences implies that the world that we perceive currently is not real.

Enough examples have been given to show that the word being unreal is a doctrine of prasthAna traya. Hence, the charge of Shankara being crypto-buddhist does not hold water.

Final word

The question mentions -

Another acarya in the line of Ramanuja, Vedanta Desika (1269–1370) wrote his famous Sata-dusini, a text expounding one hundred flaws found in Mayavada. In that work he refers to Sankara as a rahu-mimamsaka (one who obscures the true meaning of Vedanta), a bhrama-bhiksu (a confused beggar), a cadmavesa-dhari – one who is disguised in false garb, and goes on to assert that, “By memorizing the arguments of the Sata-dusini like a parrot, one would be victorious over the crypto-Buddhists.”

Ignoring all the personal attacks on Adi Shankara, there is no historical evidence that Visistha-advaitins (the school to which Vedanta Desika belongs) have consistently been successful in debates with advaitins, in the post-Desika period, by merely repeating Desika’s arguments like a parrot. Hence, the above claim and all similar claims may be taken with a pinch of salt.

PS: These points have been debated endlessly for centuries by various schools of vedAnta, without reaching any consensus. Hence, I will refrain from debates on this topic. One who does not like this answer is free to downvote.