Vajrayana and Hindu Tantricism
Sridhar SJB Rana (Chokyi Dorje)
Buddhist Himalaya: A Journal of Nagarjuna Institute of Exact Methods
Vol. IV NO. I & II (1992)
Copyright 1992 by Nagarjuna Institute of Exact Methods
Ads both Hindu Tantra and Buddhist Tantra are profound subjects and I am neither a siddha nor a pandit, I gave great trepidations in writing about these subjects. However many writers have written about them as if the two are basically the same and since the two are actually basically different, one being based on the Hindu Advaita view (or one form or the other) and the other totally based on the basic texets of Buddhism especially those as explained by Nagarjuna and his sons and Asanga\Vasubandhu groups. It behaves me to put pen to paper extricating the Vajrayana from wrong views about what it is.
That Hindu tantra may have influenced Buddhist Tantrayana or vice- versa is not the point here. And anyway, so far whatever has been writte4n about this so called influence by one or the other has always depended on which school the writer belonged to. If he is a Hindu non Tantric (who felt uneasy with Hindu Tantra) he felt that Tantra come into Hinduism through Buddhism If he was Hindu Tantric, he felt that Hindu Tantra is found in the Vedas and the Buddhist copied it. If he was a Non Tantric Buddhist again he wrote that later Buddhist copied Tantra from Hinduism etc. However, we must understand that all these are hypothesis and no solid historical proof can be given to prove any of these. There are other hypothesis too about Vajrayana but that is besides the topic.
Now coming back to our main topic, since all spiritual systems can be divided into ground, path and fruit (Bhumi, Marga and Phala) we shall attempt to show how Hindu Tantra and Buddhist Vajrayana is totally different from each other in the ground, path and the fruit.
But first of all before we go into the ground, path and fruit, let is take up the word Tantra itself and see how the very use of the word Tantra in the two systems is totally different and fully Based on each others tenets. The Hindu use of the word (as per Sir John Woodroffe and Dhana Shumsher) is etymologically split up into tananat and trayate iti tantra. Tananat means to expand or expansion (the Nepali word tannu comes from the same root and trayate means to liberate or free. What the above root words mean is to free or liberate by expansion. Expansion of what? Expansion on the limited consciousness into the infinite Braman, Chit , Chidanana, Chit-shakti, Mahamaya, para samvit, paramshiva para bindu etc. In a very simplified form, the Jiva is limited by the various Kancukas (called asta pasa). When the consciousness of the jiva breaks through these kancukas and pasas by expansion he becomes siva.
Pasa Yukta bhavet Jiva
Pasa Mukta Sadashiva.
He who is bound by the pasa is Jiva, he3 who is free of the pasas is Sadashiva. So this is the definition of the word Tantra within the hindu network.
Coming to Vajrayana, however, it must first be clarified that Vajrayana is not limited to Tantra alone, some of the names of Vajrayana are Upayana, Guhyayana, Mantrayana Upayana means it is a way of skilful means, and that is very true because the Vajrayana does have infinite methods to attain the Buddhist enlightenment to suit individual temperaments, situation, communications, predilectilons etc. and includes among its methods non tantric (technically called Sutra methods) and tantric methods too. So it is not true the Buddhist tanrtrea is limited to the use of mantras and deities only. We find within Vajrayana methods and techiniques of sutra meditation types of Vipassyana meditations on all the four mindfulness just like in the Vipassyana of the pali Buddhism. But we also find tantric Vipassyana which uses mantra and deity visualization for samatha and vipassyana. How Vajrayana used Visualization of mandals etc as Samatha- Vipasyana and how it does not contradict even the principles of the Pali texts let alone Sanskrit Buddhism is subject matter for another article, and that Sanskrit Buddhism is as old as Pali Buddhism if not older is yet another issue and that there are forms of Vipassyana within Pali Buddhism itself which uses the mandala principles, for visualisations and repetition of mantra (eg- the Laos Mountain lineages and the Dhammakaya Foundation of Thailand ) is yet another issue.
So, after classifying that there are infinite types of Vipassyana and not all of them use automatically visualization and mantras but also use pure sutra techniques. We will go into the definition of Tantra it self as per Buddhism.
Buddhism uses on of the etymological meaning of tantra which means continuum, a continuity. Another Sanskrit word for tantra, is santaan the Tibetan word for Tantra is “rgyud” which means the same thing. So the Guhyasamaja Tantra defines Tantrs as “ Tantra is continuity and this is Threefold: Ground, Path and Fruit.”
The above tantric texts also calls Tantra- Prabandha. Though both Hindu and Buddhist use Prabandha, even here the meaning chosen is again different. For Hindu Tantra, Prabandha means systematization and to the Buddhist Tantra, Prabandha means continuity and integration.
Rong Zom Chokyi (11th century Tibetan and a contemporary of Marpa) who was a Sanskritist, prefers the meaning of integration in the sense of the integrating into one whole (or holistic) of the different aspects and processes of personality. However, the meaning of continuum has become more popular than the integration.
Of course within Buddhism, Tantra is so multi faceted ( that is why it is called upayayana- the way of skillful means, that no one defining word \ meaning like “integration” or “continuum” can really fully satisfactorily explain away its true significance within the Buddhist network. So then it would actually require multiple definitions to be fair to it. Long Chen Rabjam- Pa (1308-1363) a great Nyingma Tilbetan Master has thus in his ‘ thegpai Chog Rimpooche Zo’ (Uttama Yana Ratna Kosha) has given a series of definition. In its svarupa (essence) tantra means the presence of Vidya (Tibetan Rigpa) and its operation. It can also be divided into two (a) Paratantra which means the true nature (swabhava) of the mind and (b) the literary works which point out the fairness (swarup) etc. The greatmaster Jigme Tenpai Nyima (Skt. Abhaya Dharma Bhanu) defines tantra. “ The attainments to te realised is tantra of ground (Bhumi) or base (Asraya). That by which one realizes the above through the use of skillful means (Upaya Kausalya) is the Tantra of path (Marga). The goal which one perfects (Siddhi i.e. enlightenment: freedom form sorry:) is the Tantra of result.” In this way the ground path and the fruit (bhumi, marga and phala) are limited I;n the same continuum i.e. Tantra. The base (bhumi) is what is primordially. This however is not something existing like the Braman or parasamvit of Hindu Tantra. Nor is it beyound existing and non existing like the Braman of sankara it is free of such concepts as existing or non existing (caatuskoti vinirmuktam), It is a non- conceptualwisdom but does not have an ingerent existence (niswaghya siddha). The bhumi is spoken of in terms of the two truths (satya dwaya of Nagarjana) . The ultimate truth and conventional\ relative truth of Nagarjuna is not the same as the two truths of Sankara. Sanlara’s ultimate truth is an ultimately existent (paramartha satta) whereas there is no such thing as an ultimately existent (paramartha satta) in Buddhism. In other words Buddhist tantra does not have an Asraya or Bhumi on Which this universe is based. The universe is baseless, Groundless. This baselessness or groundless or groundlessness is a more refined ferm of Anatma in that er es automatically inclusive of Anatma. The path is the skillful blinding of means and wisdom (upaya and prajna) to actualise the bhumi which is groundless wisdom and the fruit (phala) is the actualisation of the groundless wisdom, also called Vidya (Rigpa), Sahaja Jnana (Lham Cigkye Yeshe) Prakrita Agrah Jnana (Ma cho thamal gyi shepa) etc.
as con be seen; the whole purposes of Hindu Tantra is to acrualise ther basic
ground of the samsara which is called by various names like Brdaman, Parasamvit,
Mahamaya etc. which are all extension of a belief in an Atma where as the
Buddhist tantras are geared towards the realisation/ actualisation that the
Samsara and Nirvana both are Groundless ie, have no ground or base which is an
extensionm of the belief in Anatma also called Sunyata, Pdrajnaparamita,
This time we took the definition of tantra in the two system to see that the very definition of the word are different.
Differences In Base, Path and Fruit (I)
We shall now took the definition of tantra in the two system to see that the very definition of the word are different.
The base of Hindu tantra practice is of Advaitism in one form or the other. The Kashmir shaiva tantra call itself very clearly Shaivadvaita and the Shakta tantra calls itself Shaktadvaita. Needless to say Hindu Tantra is not all unanimous in vouching for advaitavada. So there are forms of Hindu tantra which border on the Visistadvaita of Ramanuja and tha dvaitavada of madhavacharya . But for lack of spaci we shlll not deal with (special nondualist) Visistadvaita and (dualistic) dvaitavada schools of Hindu tantra as no effort is required to show that such forms of Hindu tantra are totally different from Buddhist tantra. The ground (bhumi) of the Hindu tantra can be summed up in the work Shiva Shaktyatmakam Viswam ie, Shiva and Shakti are the essence of the universe. In other words Shiva Shaktis is/are the base, the ground of the base. The universe is the lila (play) of the two. The universe is based or grounded in Shiva Shakti, comes out of Shiva. Shakti as its lila (play) and remains grounded in Shiva Shakti at the end. Anyu one who knows the advaita vedanta can see that if Shiva Shakti were replaced by Brahma Maya, this view is not very different from the advaita vedanta of Sandaracharya. Of course, Since there are many forms of Hindu tanrtra like Shakta tantra. Shaiva tantra and even within Shaiva tantra there are the Dachinachara and the vamachara and the Siddhantachara and Kaulachara, there are slight variations to the Basic ground as given above. But basically and broadly speaking they would all agree to ‘Shiva Shaktyatmakam viswam.’ So it becomes necessary to understand what Shiva and Shakti means.
Shiva is the static aspect of the universe and Shakti is the dynamic in; the macrocosmic sense. In the microcosmic since Shiva is the basic awareness aspect of Mind (as per Shiva Surtra) which in being only aware and not able to do anything else but be a witness (Sakthi of the Upanishads) is static. Shakti is the moving thoughts, emotions etc. of the Mind which is ever in movement (opandana of the Spandana Karika).
The base of man is the interplay (lila) of these two (Kama Kala Vilasa ie- Erotic play of Kama- Shiva and Kala- Shakti.) Likewise the base of the cosmos is the same Shiva Shakti evoked in a macrocosmic scale. In the words of the Pratyabhigya Sastra the bgase is the ultimate reality is Prakash Vemarsamaya. Prakash is the eternal light without which nothing con appear and it is Shiva. Vemarsa is Shakti, the swabhava of Shiva. It is so to speak, the mirror, in which Shiva realizes his own grandeur, power, beauty. Vimarsa is the Kartitva Shakti of Shiva. The ultimate reality is cit or Pasrasamvit, the non –relational consciousness which is Kama Kala , Shiva Shakti, Prakash-Vimarsa.
Whether the emphasis is given to Shiva or Shakti depends on whether one is seeing the ultimate reality from the eyes of the Shaiva Tantra or Shakta Tantra. so this is the ultimate reality (the Paramartha Satta) of the Hindu tantra which substitutes only in the mane t he vedantic Brahman and is two rather that only one (Brahma) as in the Vedanta. However, like the Brahman, these two Shiva and Shakti are actually one. Therefore they truly exist. otherwise they could not be the Paramartha Satta, the ultimate reality.
The Buddhist bhumi is totally different. The ground of the Buddhist tantra can be described in various ways. The Sutra Mahamudra and the Mahasandhi traditions define the ground as Primordially Pure which is just a technical way of saying Primordially Empty which again in Theravada language woukd boil down to Anatma. Of course Primordially Pure goes deeper than just Anatma, but again this is another subject. In the Sakya tradition of the Tiabetan Vajrayana, it is said Sal tong zung juk ryu yee chen key dang or in Sanskrit 'Prabhaswar sunyata yuganadha cha sahaja hetu' which means 'Clarity, Emptiness and their two in one are the spontaneously born Cause- Base. Another term used is Groundless Awareness which means Empty Awareness. What all the above words (and many others mean is that the ultimate truth is that there is no ultimate reality/existent (paramartha satta) that one can grasp or hold to as something. And itits exactly this non-grasp ability because there is nothing to grasp because everything is ultimately impoty of real existence or that there is no Atman (truly existing self) whether in the person (pudgal nairatmya or in the phenomenal world- dharma Nairatmya) that is the ground of Buddhist tantra.
So Hindu tantra has a Paramartha satta by the name of Parasamvit which is the union of Shiva and Shakti as its base which is to b
e actualised as its phala (fruit). But Buddhist tantra has anatma or emptiness of real existence of all Dharma and Pudgal. Including the mind which is technically in tantrik terminology called groundless or unity of Emptiness and Clarity, Emptiness and Appearance, Emptiness and Bliss or Primordially Pure as its base to be actualized as its frit. In another words Buddhist tantra is based on the non existence of any Paramartha satta and is geared towards the realization/actualization of this existential fact, whereas Hindu tantra is based on a Paramartha Satta and its actualization.
It is obvious that the very ground or base (Bhumi) on which these two systems of tantra are based are diametrically opposed.
One on the realization by a Wisdom consciousness of the non- findability (anupalabdhi) of any sort of Paramartha satta (ultimate reality) anywhere and the other the actualization or realization of some Paramartha satta (an ultimate reality that truly exists). Needless to say this is the basic difference between Buddhism and Hinduism as a whole.
Difference In Their Base, Path and Fruit (II)
Many persons are confused about the fact that both Vajrayana and Hindu tantricism use mantra and deities in their practices as a proof that their practices are basically the same.
Needles to say, it is based only on surface understanding of both Hindu tantricism and Buddhist Vajrayana.
First of all, the very base ie, the foundation on which Hindu tantric practices, is to realize an Ultimate real/Existent (Paramartha Satta).
Where as the foundations of Buddhist tantra is to realize that there is no Paramartha Sata ie there is Emptiness of the Paramartha satta.
Anybody can see that to realize there two diametrically opposed base would require an almost equally diametrically opposed path.
So just because both happen to use mantras and deities it is naive to state that these practices are the same or even similar.
To Buddhism all practices (meditation, mantra- visualisation), no matter what name you give it, are done to actualize some thing. Be that some material gain or some subtle form like the Braman/Atma of Vedanta or the Shiva-Shakti of Shaiva and Shakta tantra.
They are only the extended versions of materialism. All of them are geared towards the achievement of one thing or the other; be it gross or subtle.
The strategy to free oneself from this sorrowful world by creation/fabricating (Parikalpit) on Absolute/Really Existing/Eternal, unchanging is merely a subtle version of the strategy of escaping from the problems and boredom of life by escaping with the help of achieving money or other such things.
All of these are escapists strategy and are labeled materialistic solution.
By the same logic, the search for the eternal Unchanging Atman/Shiva Shakti and escaping to them from the sorrows of life is called spiritual materialism (adhyatmic bhautikvada) in Buddhism.
The only true freedom must be a facing of the actual situation of the world as it is (tathata) without creating escapist dreams or fabricating dream realities unlike the world and which there fore is unchanging, really existing and so on.
The whole of Buddhist path is geared towards teaching or making the individual re-learn how to face the actually reality (Yathabhuta) and not see the world according to a conditioned visions, whether they are ordinary human conditioning or learned conditioning through religions for example, and eternal Atman of the Upanishads.
Whereas according to Buddhism, the whole of Hindu tantricism is geared towards the realization of exactly such a fabricated (albeit refined) dream like the Atman.
Her, it is important to notice that it is not possible that Hindu tantricism which is based entirely in search of an Ultimate Reality separate from this samsara itself as Nirvana can have the same practices as Buddhism.
Hindu tantric practices are based on the belief that the ten Mahavidya as (ten great wisdom deities) are really existing and by continuous 'japa' of their mantra, one will slowly get their grace through which one will slowly identify oneself with them and become the Mahavidyas themselves and be liberated.
The progress of the practice is from Dasoham (I am slave) where the practitioner believes in the deity as his/her Master or Lord. With continuous 'japa' of the deity (as the saying goes japad shiddi japad siddhi, japad siddhi no samsaya meaning siddhi is attained through japa...no doubt) one slowly merges into the deity (like Kali, Tara or Tripurasundari) and becomes one with the deity.
At this stage it is called Soham (that I am ie., I am Shiva/Kali).
Then with more japa or more accurately more japa of the mantras got in series called Krama Dikcha, he/she becomes completely dissolved into kali/Tripurasundari so that no 'I' is left anymore and only the deity is left.
At this stage it is called Naham (no me). And this is the Acme of Hindu tantra where the personality has completely dissolved into one of the ten (dasa Mahavidya) and what is left over is the ultimate reality called by whatever name-Kale, Dhumavait so on.
It is said in the Mahanirvana Tantra 'Krama dikcha yuttor devi, Kramat sambhur bhver' (As the person becomes endowed with Krama Dikcha (serial mantra initiation) gradually the person becomes Shiva.)
The actual modus operandi is that the disciple first receives the initiation of one of the Mahavidya from a Guru. Hi learns the mantra and dhyana (visualisation).
He, then, does japa dhyana of the deity ie., he visualises the deity in front of him and repeats the nyasa and mantra.
Nyasa is placing the deities in different part of the body and varies with different Kramas.
So one imagines various deities (who are part of the Karma of the "Mula Devata" in different joints of the body by touching that part of the body with ones, fingers and repeating the mantra.
Exactly how it is done varies with the various kramas.
The rest depends on doing more and more japa (as said above) and completely getting oneself absorbed into the visualised deity until their unity and finally only the deity is left.
In Buddhist language this is more and more samatha (absorption) until identification and loss of self occurs.
It has to be mentioned that all forms of Hindu tantra are not unanimous in their basic concepts unlike all forms of Buddhis tantra (who are all unanimous in there basic concepts).
1. Some forms of Hindu tantra (Kasmir Shaivism) believed that Shiva is in one's own mind; but the majority believe that deities exist independently and the personality which is unreal dissolves into the Real Deity.
All forms of Buddhist tantra believe the essence of all deities is ones own mind.
2 Whereas visualisation and mantras in Hindu tantra are limited to the ten Mahavidyas as the highest forms of deities, but in Buddhist tantras these are. relegated to the positions of only protecteors of the Dharma (dharmapalas) who con only clear obscuration in a practitioners, practice but not really give enlightenment.
But besides these dharmapalas like Mahakala or Mahakali, Buddhist tantras also gave visualisations and mantra of Gurus, Bodhisatvas like Manjushree, Avalokitesvara, Vajrapani and Ista devas.
These, it is made clear-especially the Ista devas (called Yidam in Tibetans) are your own Mind and not something separate. And it is only the proper use ie., samatha- vipassyana of Mind Deities (the word Yidam in Tibetan means Mind Bond) that can liberate.
Simply repeating mantras and visualising is not only said not to liberate automatically but can also lead to more subtle forms of spiritual materialism according to Buddhist tantra.
Among the Newars, the priests of Hindu Newars are called Deobhju whereas Buddhist Vajrayana priests and called Gubhaju. It Showa clear differences in emphasis to Hinduism Devas are the supreme and represent various forms of god, that is why the priest is called Deobhaju. But for Buddhism Deva are manifestations of the mind and the mind and the Guru are one. So the Guru is the supreme. He creates the devas and introduces them to the disciple. He and ones own mind are not really two.Further more there is no God (Ishwar) In Buddhism so the question of the devi/devatas in Vajrayana becoming manifestation of god (Ishwar) is completely out of question. That is why the priests of Vajrayanas are called Gu(ru)bhju. It is also not surprising that manuy western scholar call Tibetan Vajrayanas as Lamaism. Although this is inaccurate and actually wrong since there actually is no such thing as Lamaism. however it is true that the word lamas means guru and the lama is supreme in Tibetan Vajrayana as well.and Lama is the Tibetan word for the Sanskrit Guru. The Buddha himself, in all forms of Buddhism is the Supreme Guru and not by any means some sort of replacement for god in the other forms of religion. So the Devas are manifestations of the mind itself given architypal forms for quick purification and Samatha (called Shiney in Tibetan) i.e. quietening the mind. They are never really independent of the nature of mind which is called Empty and Luminous in Tantrik terminology. So all the deities and their consorts are sons are only metaphoric ways of expressing manifestations. It is totally stupid to say, as some so called Vajracharyas influenced by Theraravad have written that Vajrayana has created many Buddhas out of the one Sakyamuni Buddha and given them wives and children. Vajrayana has not created replacements for the historical Sakyamuni. What Vajrayana has done is discovered easier ways to purification and Samatha through Visualising metaphoric forms of the enlightened mind of Sakyanumi. As I have already mentioned the firm of Vippassyana most common in Vajrayana is through Chittanusmriti ie. mindfulness of the mind. Visualising of various mandala like forms and spontaneous appearance of Devas in meditation of this kind is found not only in Vajrayana but also the Theravada Buddhist tradition of the mountain tradition of Laso. So these Theravadin."Vajracharyas" who have tried to make fun of the mandalas of Vajrayana are also criticising their own Theravada traditions as practiced in the Laos mountains. I believe this is breaking of one of the major shilas in the Theravad tradition (creation disturbance in the Sangha).
Hindu tantra certainly does not use the Devi/Devata in this way except in the Kashmir form of Shaiva tantra as mentioned before.
As mentioned earlier the ten Mahavidhyas are the ultimate deities in Hindu tantra who represented God or Ultimate Reality depending upon which amnaya (way) of Hindu Tantra one follows. However in Buddhist tantras as already mentioned non of the visualised represent either god or the Ultimate Reality (Paramartha Satta) and this has already been clearly explained in the foregone pages.
As already said what they request is the mind or the Guru. There are various classes of deities (Visualisable form would be more accurate in Buddhist tantra) whose concept of Devas is so drastically different form that of Hindu tantra that they can not in any way be called even remotely similar. The various classes of forms used for meditation in Vajrayana are: 1) Guru 2) Buddhas and Bodhisatvas 3) Yidam 4) Dakinis and Dharmapala.
1. Guru: Who Represent the entire lineages from Sakyamuni till now. Since every teacher that comes from an unbroken lineage represents every other in the lineage, their enlightenment being the same, it is not necessary that only Sakyamuni represents the Guru. So in the Vajrayana tradition not only Sakyamuni but also Padmasambhava, Naropa, Milarepa, Virupada, Karmapa and a host of others who represented the Enlightenment of Sakyamuni are also used as Guru- Visualisation. This is totally non-existent in Hindu tantra which has only Guru Puja which is done to ones own Guru on certain days like Guru Purnima; but no meditation which uses the Guru for Samatha- Vipassyana is found. Furthermore the concept of a pure lineage, unbroken so that any one lining Guru's mind is the same as any othey before him (which is a technical way of saying that they have all experienced the same true enlihgtenment and not defferent states as per each Guru and certainly does not mean have lost their individuality or identity such as a concept does not exist in any form of Hinduism except those influenced by Buddhism. What I am talking about is the transmission from generation to generation of exactly the sami enligheinment state without distractive changes, not transmission of concepts or ideas from generation to generation which is found in Hinduism also. This concept of the same (pure) enlightened state "being tranmitted" generation to generation without any breakage (which would open up distortions) is very important for all forms of Buddhism which emphasis meditation and the ewperience of experience of enlightenment and especially for Vajrayana which is one of the most practically oriented forms of Buddhism.
2. Buddhas and Bodhisattvas: Although Buddhas and Bodhisattvas technicall came under the heading Guru, here, We are talking about forms like the five Tathagatas (called by the misnomer pancha Dhyani Buddhas) and Manjushree. Avalokteshvara, Vajrapani etc. Of course all of these represent the Guru too. The panch tathagata represent the essence (which is primordially pure) of the five passions in us enumerated as Akshobhya for krodha, aggression, Vairochan for moha/stupidity, narrow-mindedness, Amitabha for Kama/passion desire. Amogha Siddhi for paissunya/jeolousy. Ratnasambhava for manas/pride. If these passion (kleshas) were not primordially pure (which can be seen as either empty of real existence (Niswabhavasiddha) for begining less time or as non-dual widsom (advaya jnana) from begining time. One could never be free of them as they (the kleshas) would really exist eternally. This primordial purity of each passion os represented by the five tathagatas. The pancha tathagata also represent the five skandhas in their true nature (not as how they appear to the deluded mind) which again can be called as non-dual wisdom or emptiness (which, when understood, property are not contradictory but this is a subject by itself) It is also important to mark the use of the word advaya as opposed to the Hindu advaita which are contradictory concepts and not the same at all -as many Hindu and Buddhist scholars have believed. So coming back to the pancha tathagatas, anybody can now see that they are not subdivisions of Sakyamuni nor can you speak of them as personalities who have wives and children. The consorts and sons are also equally metaphorical automatically.
Furthermore these kinds of devas (Bodhisattvas and Buddhas) are used again like the Gurus for specialized forms of Samatha- Vipassyana: and needless to say such methods are not found in Hindu.
3. Istadeva (Yidam in Tibetan): The word Yi-dam translates something like Mana bandha in Sanskrit. All these dieties are Mind-Bonds/Mind Bound. So evidently the use of the word. Istadeva is not the same as in Hinduism. Although in both Hibduism and Buddhism you can speak of Istadeva as pr\ersonal deity, in Hinduism he is someone who es the goe and master above one and the one into which one dissolves ones little self wnereas in Buddhism the Ista being the beaarest or poersonal deity symbolosong ones own mind. the true nature (svarupa nof the deity) is the same as the nature of mind on which one does vepassyana of the chittanusmriti group. So Istadevas are merely ones own mind given vesualisable forms and vipassyana on them os therefore Chittanusmriti. Using what is called the Utpattikrama and Sampannakrama (often translated into English as development/generating), creative stage which is the tantrik way of doing Samatha and uses the Buddhist meditative principle called devanusmriti (called Devanussati in the Pali canons, and fulfillment/completion/perfection stage which is doing vipassyana on the true nature of mind. This vipassyana on the true nature of mind is the ultimate meditation in all forms of Buddhism-Theravada, Mahayana Sutra or Mahayana tantra traditions.
Hinduism has no concept of practice similar to the Yidam practice of Vajrayana. All Yidams (Istadevas) belong to the five families (pancha Kula) ie. the family of the five Tathagatas Since the five Tathagatas are linked with the five predominant defilements practioners are also divided into these five kulas.
So each person chooses an Istadeva out of the Kula he belong to or is chosen by his guru. The deity, his emotional tone, the practice related to him are suitable emotionally for that particular practioner who belong to the same family. That is why the Istadeva practice is very swift in ripening in the mind to make it ready to recognize or realize or actualize the nature of mind fully. Whereas in Hindu Practice, it is the deity that gives liberation through his grace, in Vajrayana the Yidam (Istadeva) is the major support or aid for the spontaneous arising of the actualization of the nature of mind and it is only the actualization of the nature of mind that gives liberation. The various deities used for Yidsam practice depends on which of the four tantras (or six tantras as per the old schools) is used to practice Samathavipassayana. The six/four tantras are a topic by themselves; but the fourth tantra called the Anuttara tantra (unexcelled tantra) is usually used as the quick way to enlightenment. Some of the Istadevas of the Anuttara tantra are Kalachakra, Mahamaya. Guhyasamaja. Chakrasamvara, Hevajra and so on, none of which are found in any Hindu tantric scriptures.
4. Dakinis and Dharamapalas: The fourth group of devas used are dakinis, dharmapalas and lokapalas. These deities correspond to the devas found in Hindu tantra, Mahakala/ Kali etc: but they are used as protectors and clearer of obscurations on the path of enlightenment. So the 10 Mahavidyas (with the exception of Tara) are not givers of enlightenments, but rather helpers on the way who clear away obstacles to practice and enlightenment in Vajrayana. So even with the group of devas (which seem to converge and to a greater degree to Hindu dieties) their use is totally different. They are not even similar. But even Sri Lanka Theravada uses Indrra as a Dharmapala (protector of dharma), so such use of Hindu deity is found in all Buddhist tradition.