There are several Suttas in the Pali Nikāya which address emptiness, but it seems that its meaning is not always the same. This article investigates the concept of emptiness in its different occurrences in the Pali Nikāya, and tries to find the exact meaning of emptiness. The result then we will compare to the concept of emptiness as described in the Mahāyāna scriptures in order to see similarities or discrepancies between them.

The occurrence of emptiness in the Pali Nikāya can be classified into three kinds according to an analysis (Bhikkhu Thanissaro 2010): as an approach to meditation, as an attribute of the senses and their objects, and as a state of concentration. According to this analysis, these different forms of emptiness ultimately serve to the same aim of liberation from suffering.

The first meaning of emptiness as ‘empty of disturbance,’ or ‘empty of stress’ is the basic meaning of emptiness regarding a process of meditation in which the meditator examines the presence or absence of certain perceptions, which he feels as subtle disturbance or stress, in order to remove those perceptions in favor of a more refined state with less disturbance. This process then continues, relating to four formless meditations, until acquisition of the realization that even the highest stage of the perceptions of the highest dimension is mentally fabricated. With this realization comes liberation from the mental fermentations of sensual desire, becoming, and ignorance, and the knowledge that there will be no more rebirths. The second meaning of emptiness is concerned with the nature of the world or things, which is empty of a self or anything pertaining to a self. According to the analysis, this meaning of emptiness is actually not different from the first meaning of emptiness when the meditator realizes even the calm and the insights achieved in the highest meditation as empty of a self or anything pertaining to a self. So the analysis says when the meditator removes labels of “I” or “mine” from his own insights and mental states, they will be seen simply as instances of stress arising and passing away. The third kind of emptiness, as a state of concentration, is described as another way of using insight into emptiness of the senses and their objects as a means to attain liberation. It can be a kind of combination of the first and the second kinds of emptiness. So whatever object the meditator takes as his concentration, in adopting emptiness as an approach to his meditation, the achieved perceptions are dropped, and ultimately the highest form of emptiness is reached, free from all mental fabrication.

Now this classification into three kinds of emptiness seems not so proper because there is not a clear distinction between the first meaning of emptiness and the third one, both being eventually concerned with the four jhānas and four formless meditations leading to the final liberation. Therefore the first and third meanings of emptiness, in the present paper, will be treated together under the analysis of emptiness in relation to meditation. Instead, the abiding in emptiness by the Enlightened Ones will be regarded as an essential meaning of emptiness because the abiding in emptiness by the Enlightened Ones seems the reason why they are not contaminated by the defilements of the world while still living in the secular world. This meaning of emptiness also seems to play an important role in Mahāyāna Buddhism when it emphasizes the concept of the Bodhisattva who further maintains the worldly life without clinging to it in order to help other beings to be freed from suffering. The reason that the Bodhisattva can be detached from sensual desire while living in the secular world lies in their practice of abiding in emptiness just as is the way of the Enlightened Ones. With this overview we will see the details about each meaning of emptiness in the following.

Reference to emptiness in the Pali Nikāya is used as a description of the final liberation of mind resulting from a series of meditations. Among several Suttas dealing with emptiness in relation to meditation, three Suttas provide important points in discovering the meaning of emptiness. They are the Culasuññata Sutta (MN 121), the Aneñjasappaya Sutta (MN 106), the Mahāvedalla Sutta (MN 43) and the Mahāsuññata Sutta. Firstly, concerning with the meaning of emptiness during meditation, the Culasuññata Sutta (MN 121) provides a detailed description on what is to enter and remain in emptiness. It begins with Ānanda’s question of whether he remembered correctly when he thought that the Buddha once said, “Now, Ānanda, I often abide in emptiness.” The Buddha approved that he heard correctly and gave a discourse on a series of entries into emptiness which goes from the perceptions of wilderness and the earth through the perceptions of four formless dimensions to the signless concentration of mind in the final stage of meditation. And he discerns that this mode of perception is empty of the perception of the dimension of neither perception nor non-perception and knows that “There is only this non-emptiness: that connected with the six sensory spheres, dependent on this very body with life as its condition.” But then while his mind still takes pleasure, finds satisfaction, and indulges in its signless concentration of mind, there comes the notion that even this finest state of perceptions is fabricated.

So with the notion of the finest perceptions as fabrication and impermanent, comes freedom from the taint of sensual desire, becoming, and ignorance i.e., from the round of rebirths. This realization is the level of emptiness that is superior and unsurpassed, about which the Buddha said of contemplatives and priests in the past, present, and future “all enter and remain in this very same emptiness that is pure, superior, and unsurpassed” (MN 121, Culasuññata Sutta). The dividing point between the liberation from rebirth and return to rebirth is the awareness that even the finest stage of concentration is fabricated & mentally fashioned and so subject to change.

This pivotal moment of awareness of fabrication and impermanence of the finest perceptions is more precisely described in the Aneñjasappaya Sutta (MN 106), clearly illuminating the exact reason for the final liberation. Accordingly, a noble disciple experiences each state of perception until reaching the perception of the dimension of neither perception nor non-perception.

Here a monk, having experienced and abandoned all previous perceptions including the perception of the dimension of nothingness, obtains equanimity in the dimension of neither perception nor non-perception. In the dimension of neither perception nor non-perception he is satisfied with his achievement and remains there enjoying its taste.

That which is here preventing his liberation is the fact that he relishes the equanimity obtained in this state. With this enjoyment he is now clinging to the dimension of neither perception nor non-perception which the Buddha called “the supreme clinging” because it lies on the threshold of total Unbinding, Nibbāna. In contrast however, there is a case where a monk can get rid of this last hindrance and achieve total liberation from saṃsāra.

Here the monk doesn’t delight in the equanimity obtained in the dimension of neither perception nor non-perception. Therefore, he is not clinging to it and without any clinging he is totally unbound. Now if we compare this Sutta with the previous Culasuññata Sutta, we can see the signless deliverance of mind is simply expressed as equanimity without adding a particular name. Instead the focus here is given to the clinging which hinders the final liberation, naming it ‘the supreme clinging.’ When a monk, passing through all perceptions including the perception of the dimension of neither perception nor non-perception, can perceive “this is identity as far as identity extends,” the final liberation which is the Deathless, the liberation of the mind without clinging will be obtained.

Through the analysis of the Culasuññata Sutta and the Aneñjasappaya Sutta, we can say that emptiness is related to the deliverance of mind which is attained through emptiness in the final state of meditation by abandoning all perceptions experienced in the previous dimensions including the dimension of neither perception nor non-perception. This result occurs by empting the present perceptions; therein the last entry into emptiness is caused by the notion of fabrication and impermanence of the finest perceptions achieved in the last dimension, whether perceptions of the dimension of neither perception nor non-perception or the signless concentration of mind. Without the realization of fabrication and impermanence of achieved equanimity, one cannot be liberated from the round of rebirths because consciousness is dependent on it and clinging to it so long as there is enjoyment of the achieved equanimity.

1So evaṃ pajānāti―“ayampi kho animitto cetosamādhi abhisaṅkhato abhisañcetayito.” “Yaṃ kho pana kiñci abhisaṅkhataṃ abhisañcetayitaṃ tadaniccaṃ nirodhadhamma’nti pajānāti. Tassa evaṃ jānato evaṃ passato kāmāsavāpi cittaṃ vimuccati, bhavāsavāpi cittaṃ vimuccati, avijjāsavāpi cittaṃ vimuccati. Vimuttasmiṃ vimuttamiti ñāṇaṃ hoti.” “Khīṇā jāti, vusitaṃ brahmacariyaṃ, kataṃ karaṇīyaṃ, nāparaṃ itthattāyā’ti pajānāti.”  2Idhānanda, bhikkhu ariyasāvako iti paṭisañcikkhati―ye ca diṭṭhadhammikā kāmā, ye ca samparāyikā kāmā; yā ca diṭṭhadhammikā kāmasaññā, yā ca samparāyikā kāmasaññā; ye ca diṭṭhadhammikā rūpā, ye ca samparāyikā rūpā; yā ca diṭṭhadhammikā rūpasaññā, yā ca samparāyikā rūpasaññā; yā ca āneñjasaññā, yā ca ākiñcaññāyatanasaññā, yā ca nevasaññānāsaññāyatanasaññā―esa sakkāyo yāvatā sakkāyo. Etaṃ amataṃ yadidaṃ anupādā cittassa vimokkho.  3Idhānanda, bhikkhu evaṃ paṭipanno hoti―no cassa, no ca me siyā; na bhavissati, na me bhavissati; yadatthi, yaṃ bhūtaṃ―taṃ pajahāmī’ti. Evaṃ upekkhaṃ paṭilabhati. So taṃ upekkhaṃ abhinandati, abhivadati, ajjhosāya tiṭṭhati. Tassa taṃ upekkhaṃ abhinandato abhivadato ajjhosāya tiṭṭhato tannissitaṃ hoti viññāṇaṃ tadupādānaṃ. Saupādāno, ānanda, bhikkhu na parinibbāyatī’’ti.  4Idhānanda, bhikkhu evaṃ paṭipanno hoti―no cassa, no ca me siyā; na bhavissati, na me bhavissati; yadatthi, yaṃ bhūtaṃ―taṃ pajahāmī’ti. Evaṃ upekkhaṃ paṭilabhati. So taṃ upekkhaṃ nābhinandati, nābhivadati, na ajjhosāya tiṭṭhati. Tassa taṃ upekkhaṃ anabhinandato anabhivadato anajjhosāya tiṭṭhato na tannissitaṃ hoti viññāṇaṃ na tadupādānaṃ. Anupādāno, ānanda, bhikkhu parinibbāyatī’’ti.

The simplest explanation of the deliverance of mind by emptiness is found in several Suttas such as the Mahāvedala Sutta (MN 43), the Suññataloka Sutta or the Godatta Sutta (SN 41:7). The long process of meditation toward liberation is simply condensed into a single concentration on the emptiness of a selfhood.

So the liberation comes with the awareness that ‘this is empty of a self or of anything pertaining to a self.’ Therein it is not clear in this Sutta what ‘this’ means. The answer we can find in the Suññataloka Sutta (SN 35:85), which says the world is empty because it is empty of a self or of anything pertaining to a self.

After the description of the world as empty of a self or of anything pertaining to a self, concrete elements of the world are enumerated, each of which is accordingly empty of a self or of anything pertaining to a self. They are eye, forms, eye-consciousness, and eye-contact. Likewise the other organs of ear, etc., their object of sound, etc., nose-consciousness, etc., and nose-contact, etc. are all empty of a self or of anything pertaining to a self. So the meaning of ‘this’ in the above Mahāvedalla Sutta can be either the world or each of six organs, six external objects, six kinds of consciousness and six contacts. Or we can simply say that persons and things are empty of a self or anything pertaining to a self. The deliverance of mind through emptiness can be said to be established when one realizes that persons and things are empty of a self or anything pertaining to a self.

The deliverance of mind through emptiness actually refers to Nibbāna which can also be expressed with other names. Above when we dealt with the Culasuññata Sutta, we saw that the final state of meditation is called “Signless concentration of mind,” and if a monk doesn’t take delight in that state, his mind is liberated from the taint of sensual desire, becoming, and ignorance, which brings the knowledge that it is liberated. Therefore, the liberation of mind through emptiness is there related to the signless concentration of mind. And there are Suttas which deal with four concentrations for the deliverance of mind i.e., the immeasurable deliverance of mind, the deliverance of mind through nothingness, the signless deliverance of mind, and the deliverance of mind through emptiness, saying in one way they are different in meaning and different in name, and in another way they are one in meaning and different only in name.

The way in which they are different in meaning and different in name is explained as follows in the Mahāvedalla Sutta (MN 43). The immeasurable deliverance of mind refers to the case when a monk abides pervading above, below, and all around, everywhere and in all respects to the all-encompassing world with a mind imbued with equanimity, abundant, exalted, immeasurable, without hostility and without ill will. The deliverance of mind through nothingness is attained when a monk enters upon and abides in the dimension of nothingness with the awareness that ‘there is nothing.’ As we have already seen, the signless deliverance of mind is attained with non-attention to all signs by which a monk enters upon and abides in the signless concentration of mind, while the deliverance of mind through emptiness comes with the emptiness concentration of mind through which one comes to know that persons and things are empty of a self or anything pertaining to a self.

These four deliverances of mind are, however, one in meaning in that they all refer to Nibbāna. So in the Mahāvedalla Sutta about the immeasurable deliverance of mind the following is said.

Likewise, about the deliverance of mind through nothingness and the signless deliverance of mind the same is said but with minor change in the characterization of lust, hate, and delusion. So to the deliverance of mind through nothingness, the expression “Lust is something, hate is something, delusion is something” is given, while about the signless deliverance of mind the description “Lust is a maker of signs, hate is a maker of signs, delusion is a maker of signs” is found. Therefore these three deliverances of mind are empty of lust, empty of hate, empty of delusion. And about the deliverance of mind through emptiness, no explanation is necessary because it is already empty of lust, hate, and ignorance by definition. It is in this way that these four deliverances are one in meaning and different only in name.

5Katamā ca, bhante, suññatā cetovimutti? Idha, bhante, bhikkhu araññagato vā rukkhamūlagato vā suññāgāragato vā iti paṭisañcikkhati―‘suññamidaṃ attena vā attaniyena vā’ti. Ayaṃ vuccati, bhante, suññatā cetovimutti.  6Yasmā ca kho, ānanda, suññaṃ attena vā attaniyena vā tasmā suñño lokoti vuccati. Kiñca, ānanda, suññaṃ attena vā attaniyena vā? Cakkhu kho, ānanda, suññaṃ attena vā attaniyena vā. Rūpā suññā attena vā attaniyena vā, cakkhuviññāṇaṃ suññaṃ attena vā attaniyena vā, cakkhusamphasso suñño attena vā attaniyena vā.  7Rāgo kho, āvuso, pamāṇakaraṇo, doso pamāṇakaraṇo, moho pamāṇakaraṇo. Te khīṇāsavassa bhikkhuno pahīnā ucchinnamūlā tālāvatthukatā anabhāvaṃkatā āyatiṃ anuppādadhammā.

The name of the Mahāsuññata Sutta (MN 122) leads us to expect that this Sutta deals with the concept of emptiness. Contrary to our expectations, however, there are few words about the meaning of emptiness except a short description that abiding in emptiness is discovered by the Tathāgata. With the remarks that the Tathāgata is not attending to any themes when he enters and abides in internal emptiness, then the discourse becomes mainly concerned with abiding in emptiness. According to this Sutta, abiding in emptiness begins with the preparation for it, which is to live alone in seclusion. The importance of seclusion is sufficiently presented in the Buddha’s explanation that when the Tathāgata is visited by people while abiding in emptiness, he talks with them only as much as is necessary for them to take their leave.

Next step for abiding in emptiness is to concentrate one’s mind through four jhānas. If a concentrated mind is achieved, then one should attend to emptiness internally, externally, as well as internally and externally. According to the commentary (Bhikkhu Ñāṇamoli and Bhikkhu Bodhi 1995, 1335), ‘emptiness internally’ is emptiness connected with one’s own five aggregates, and ‘emptiness externally’ is that connected with the aggregates of others. However, according to the commentary of MN 43 (Bhikkhu Ñāṇamoli and Bhikkhu Bodhi 1995, 1239), the suññta cetovimutti (the deliverance of mind through emptiness) is identified with insight into the emptiness of selfhood in persons and things, and so ‘emptiness externally’ can also be interpreted as emptiness connected with things, which seems more probable. When one attends to the emptiness internally, externally, and internally and externally, it should be observed that the mind takes pleasure or indulges in the internal, external, and internal and external emptiness. If it is not observed by the practitioner, the whole process, from the first jhāna, should be repeated again until there is the recognition that the mind takes pleasure in internal, external, and internal and external emptiness.

With this, we can see a clear distinction between the emptiness concentration and other concentrations mentioned above. In the Culasuññata Sutta and Aneñjasappaya Sutta we saw that when a meditator enters and remains in a state, enjoying the attainments of that state, no further movement to the next stage will be accomplished toward the final stage of enlightenment. Even the distinction between the final liberation from saṃsāra and return to saṃsāra lies in whether the meditator relishes the attainments of the perception of the final meditation or not. However, here the meditator should take pleasure in the abiding in emptiness. We can understand it like this.

Because, in the case of the abiding in emptiness, the fruit of the concentration is emptiness, i.e., the notion of Not-self, therefore there will be nothing to cling to and so enjoyment of abiding in emptiness becomes an inevitable element for a monk who is living in the secular world without being contaminated by the defilements of the world. The next part of the Sutta confirms that. After having confirmed the establishment of abiding in emptiness by observing that the mind takes pleasure in the imperturbable while abiding in emptiness, the monk now lives a life abiding in emptiness. While abiding by means of abiding in emptiness, whatever is done in ordinary life with the body or in speech or mind, the monk knows that “no covetousness or sadness, no evil, unskillful qualities will take possession of me” (MN 122, Mahāsuññata Sutta). It is in this way that the monk remains alert. Thereafter, as in other Suttas, the reflection of the monk goes to that of the five aggregates and any conceit of ‘I am’ with regard to these five clinging-aggregates is abandoned.

But going back to the issue of abiding in emptiness, the Buddha lastly admonishes the undoing of one who leads the holy life. So if a monk living in seclusion, when visited by people, falls into greed, and reverts to luxury, then it will lead to further becoming, and future birth. The undoing of one who leads the holy life, the Buddha says, ripens in more pain, more bitterness, than the undoing of other practitioners, and will lead even to the states of deprivation.

This meaning of emptiness concerning the abiding in emptiness is very important because it seems to provide a basis for the concept of the Bodhisattva in Mahāyāna Buddhism. The term Bodhisattva was already present in the Pali canon as Bodhisatta. There, however, it is mainly used to refer to Siddhattha Gotama i.e., the Buddha before his enlightenment. As is well known, one of the most distinguishing features of a Bodhisattva in the Mahāyāna tradition is that the Bodhisattva postpones the attainment of Nirvāṇa in order to remain in the world and to help others to attain enlightenment. This meaning of Bodhisattva is not found in the Pali canon. However, it seems that there is a clear relation between the abiding in emptiness of the Enlightened Ones and the abiding of Bodhisattva in the world. To investigate this let’s look at the verse form of the Prajñāpāramita Sūtra. The exact name of this Sūtra is the Prajñāpāramitā-Ratnaguṇasaṃcayagāthā and it consists of 302 verses on the Perfection of Wisdom (Conze 1994, 9). This Sūtra is considered one of the early Mahāyāna scriptures and it is argued that “the first two chapters constitute the original Prajñāpāramitā which may well go back to 100 BC” (Conze 1994, 10). Being an early Mahāyāna text, the following verses are considered to show the same understanding of the meaning of emptiness as is presented in the Pali canon.

The deliverance of mind is here presented as ‘coursing in dharmas as empty, signless and wishless’ and these characteristics are the same as defined in the Pali Nikāya for example in the Mahāvedalla Sutta. More importantly the Bodhisattva, thus coursing, does not experience the Blessed Rest, meaning the enjoyment of the peaceful calm attained in the highest stage of meditation. In the following the abiding in emptiness by the Bodhisattva is described and it is the same abiding in emptiness as that of the Enlightened Ones as seen in the Pali Suttas.

By comparing the dwelling of bird and fish to the dwelling in emptiness of the Bodhisattva, the fact that the Bodhisattva does not reach the Blessed Rest is emphasized. This means that the Bodhisattva dwells in emptiness while engaging with the secular world. This meaning is clearly described by the following verses which contrast a life in retreat with conceit to a life in the secular world without attachment to enlightenment for the welfare of the world.

If a Bodhisattva living in a remote place is contaminated by the conceit of superiority toward another Bodhisattva who has fulfilled in concentrations, emancipations and etc, thinking the latter does not live in the detachment of the remote forest, then the former cannot be considered to know true detachment. As a result the following is said.

The Bodhisattva who may be considered free from the notion of self is such a one who is free from the thought of the twofold vehicle and fixed on the supreme enlightenment. Here the twofold vehicle of the Arhats and Pratyekabuddhas is contrasted to the Bodhisattva. The Arhats and Pratyekabuddhas are defined here as those who are attached to and fixed on the supreme enlightenment while the Bodhisattvas as those who have set out for the welfare of the world.

In the above when we investigated the abiding in emptiness of the Enlightened Ones we saw that seclusion is recommended by the Buddha. However, in the Buddha’s discourse about abiding in emptiness, we saw that it is possible for those who abide in emptiness to lead an ordinary life in the secular world while not being contaminated by the defilements of the world.

This meaning of emptiness as the place of abiding became the basis of the concept of the Bodhisattva in the Mahāyāna tradition, and led to the contrast between the attachment of the Arhats and Pratyekabuddhas with the enlightenment and the detachment of the Bodhisattva who prefers to remain in the world. Furthermore, this remaining in the world for the welfare of the world while abiding in emptiness is presented as the perfection of the Bodhisattva ideal.

This paper investigates the concept of emptiness in three different meanings: Emptiness in regard to the highest attainment of meditation; emptiness as the nature of persons and things empty of a self or of anything pertaining to a self; and emptiness in which one should abide. Each meaning can be summarized as follows.

Emptiness in the Pali Suttas mainly occurs in relation to the highest stage of meditation in the process of achieving liberation. The critical factor which separates liberation from rebirth and return to rebirth is whether the meditator enjoys and remains in the equanimity achieved in the highest dimension or not. If the notion that even the finest perceptions achieved in meditation are fabricated and mentally fashioned and so subject to change occurs, and, as a result, the abandonment of immersion in the highest dimension ensues, the mind is liberated from the taint of sensual desire, becoming and ignorance and there is knowledge of liberation from rebirth.

The concept of emptiness is also used in regard to the nature of the world or things which are empty of a self or of anything pertaining to a self. The enlightenment realized by this notion of Not-self is described as liberation of mind through emptiness. However, the enlightenment can be also expressed as the signless liberation of mind or immeasurable liberation of mind or liberation of mind by nothingness according to which characteristic you emphasize in the final liberation.

Lastly, the most important meaning of emptiness, related to abiding in emptiness, is an essential element which enables a meditator, while abiding in the secular world, to maintain a pure life without being defiled by the world. So the great beings (mahāpurisa), like Buddhas, Paccekabuddhas, and the great disciples of the Tathāgatas, all remain and abide in emptiness. Although the Enlightened Ones, who have fully realized true knowledge and deliverance, have no need for further training, they continue to meditate on emptiness, cultivating serenity and insight. This is how they could avoid contamination by the defilements of the secular world while still living in the world.

If we compare these meanings of emptiness from the Pali canon to the Mahāyāna concept of emptiness as described in the Prajñāpāramitā Sūtras, we can see striking parallels between them. Just as the abandonment of wallowing in the attained dimension plays a critical role in final liberation in the Pali Suttas, the verse form of the Prajñāpāramitā Sūtra praises one who dwells in dharmas as empty but who does not experience the Blessed Rest and it affirms that thus abiding such a one attains the wisdom of the Sugatas (the Well Gone). The second meaning of emptiness as referring to the nature of persons and things empty of a self or of anything pertaining to a self is presented in the verse form of the Prajñāpāramitā Sūtra, when it says that such a one whose self is extinct should be considered the Bodhisattva. In relation to the abiding in the emptiness of the Enlightened Ones as described in the Pali Suttas, we also find in the Prajñāpāramitā Sūtra in the verse form the description of the Bodhisattva who, having let go the acquisition of the calm concentrations, enters again into the sensuous world, compassionate for all that lives. Therefore we can say that the emptiness concept of Pali Suttas, which have three kinds of meanings, namely deliverance of mind through emptiness, emptiness of a self or anything pertaining to a self, and the abiding in emptiness after the enlightenment, is transferred to the Prajñāpāramitā Sūtras of the Mahāyāna Buddhist tradition.