1. Development of Sunyata (Emptiness) in Buddhism

2. Buddhism and Hinduism
sūnyatā/anattā of Buddhism appeared in the context of attā/ātman of Hinduism.
Buddhism and Hinduism share many ideas.
They use some common terminology like kamma, samadhi, moksa, samsara and so on.
This has led some people think that Buddhism is just a type of Hinduism, they are the same or very similar.

3. Buddhism vs Hinduism
But when we look beyond the superficial similarities we will see that two religions are distinctly different.
Hindus believe in a supreme God while Buddhists do not.
Hindus accept the existence of individual self (jīvātman) and universal self (Brahman) while Buddhists do not accept.

4. Buddhism vs Hinduism
Hindus believe that an eternal soul or atman passes from one life to the next while Buddhists believe that there is just a constantly changing stream of mental energy that is reborn.

5. What is Atta?
attā (Sanskrit- ātman) refers to an eternal self or essence that reside permanently in human beings.
It is both owner and controller, the essential recipients of experience and agent of action.

6. Does Buddhism accept attā?
According to Kumari Swami’s interpretation:
Buddhism does not reject the existence of attā. It merely says, ‘that is not my attā’.
Both Buddhism and Brahmanism believe that there is ‘attā’ in the transcendental state.
In Brahmanism this is Brahman. In Buddhism this transcendental attā is mentioned negatively in terms of: this is not my attā; that is not my attā, either.”

7. When Buddhism denies each of the five khandhas is not attā, it does not mean that there really is no attā.
It does not mean that there really is no attā. It only means that each khandha is not ‘my attā’. My real attā is in a higher state.

8. Anatta in Buddhism
Buddhism views everything as anattā, that is, without attā.
Everything here includes material objects and the world of objects.
Buddhism does not accept that there is ‘something’ that is the real essence of all things, and subsists permanently without change.
Things arise because they are conditioned. They change and cease because their conditions change or cease.

9. Anatta in Buddhism
The gist of teaching on anatta is the negation of this fixed abiding self, both mundane and transcendent.
Buddhism asserts that this self is simply an idea stemming from misunderstanding by an unenlightened human beings, who do not perceive the true nature of the world.
People create a concept of self and superimpose it on reality. This self then obstructs them from seeing the truth.

10. Anatta as one of the Three Characteristics
Sabbe sankhara anicca:
All conditioned phenomena are impermanent
Sabbe sankhara dukkha:
All conditioned phenomena are unsatisfactory
Sabbe dhamma anatta:
All things are non-self

11. What is Śūnyatā?
Nothingness?
Emptiness
Voidness

12. Definition of Sunyata
"Śūnyatā“(Pali: suññatā) is usually translated as "emptiness".
It is the noun form of the adjective "śūnya" (Sanskrit) which means "empty" or "void".

13. Is Sunyata Innovated by Nagarjuna?
Because sunyata is a word popularly used in Mahayana Buddhism, some scholars like Stcherbatsky and T.R.V. Murti claimed sunyata to be an innovation of Acarya Nagarjuna.
Murti even went into the extent of comparing Acarya Nagajuna’s teaching an Sunyata as a ‘Copernican revolution’ in Buddhist thought.

14. Sunyata in Pali Canon The Suñña Sutta
Ananda: “It is said that the world is empty, the world is empty, lord. In what respect is it said that the world is empty?"
The Buddha: "Insofar as it is empty of a self or of anything pertaining to a self: Thus it is said, Ānanda, that the world is empty.”

15. Sunyata in Pali Canon
In S IV., it is explained that a bhikkhu can experience a deathlike contemplation in which perception and feeling cease. When he emerges from this state, he recounts three types of "contact" (phasso):
1."emptiness" (suññato),
2."signless" (animitto),
3."undirected" (appaṇihito).

16. Sunyata in Pali Canon
The meaning of emptiness as contemplated here is explained at M I. and S IV. as the "emancipation of the mind by emptiness" (suññatā cetovimutti) being consequent upon the realization that "this world is empty of self or anything pertaining to self" (suññam idaṃ attena vā attaniyena vā).

17. Sunyata in Mahayana Buddhism
The Prajna-paramita (Perfection of Wisdom) Sutras taught that all entities, including dharmas, are empty of self-nature/own-nature (svabhava)
Though we perceive a world of concrete and discrete objects, these objects are "empty" of the identity imputed by their designated labels.
The Heart sutra, a text from the prajnaparamita-sutras, articulates this in the following saying in which the five skandhas are said to be "empty":
"Oh, Sariputra, Form Does not Differ From the Void,
And the Void Does Not Differ From Form.
Form is Void and Void is Form;
The Same is True For Feelings,
Perceptions, Volitions and Consciousness"

18. Madhyamika School
Mādhyamaka is a Mahāyāna Buddhist school of philosophy. In Madhyamaka, to say that an object is "empty" is synonymous with saying that it is dependently originated.
Madhyamaka states that impermanent collections of causes and conditions are designated by mere conceptual labels.
This also applies to the principle of causality itself, since everything is dependently originated. If unaware of this, things may seem to arise as existents, remain for a time and then subsequently perish.
In actuality, dependently originated phenomena do not arise as existents in the first place. Thus both existence and nihilism are ruled out.

19. Madhyamika School
Madhyamika is seen as being founded by the monk Nāgārjuna. Nāgārjuna's goal was to refute the essentialism of sarvastivada school. His best-known work is the Mūlamadhyamakakārikā, in which he used the reductio ad absurdum to show the non-substantiality of the perceived world.
Nāgārjuna equates emptiness with dependent origination:
On the basis of the Buddha's view that all experienced phenomena (dharma) are "dependently arisen" (pratitya-samutpanna), Nagarjuna insisted that such phenomena are empty (sunya). This did not mean that they are not experienced and, therefore, non-existent; only that they are devoid of a permanent and eternal substance (svabhava).