Humble salutations to all.
Today we will discuss in brief Advaita Vedanta. It is not possible of explain such a vast system in short but still we will try to discuss just the core of Advaita Vedanta.
It is but a fact that Advaita Vedanta has the most number of followers. As we have already discussed, Advaita Vedanta bases itself on the Gaudapada Karika (Gaudapaada was Sankara's guru Govindapaada's Guru -- who wrote a karika on the Mandukya Upanishad) and the works of Sankaracharya.
The list of Sankara's works are exhaustive but in general he wrote bhashyas on the dasha upanishads (isa, kena, katha, prashna, mundaka, maandukya, taittirya, aitareya, chandogya and brihadaranya), Bhagavad Gita and the Brahma Sutras. He also wrote prakarana granthas or works explaining just a particular part of the entire philosophy but not the entire philosophy. Some of his most famous prakarana granthas are Vivekachoodamani, Upadesa Sahasri, Dakshinamurthy Astakam etc.
Sankara had four main disciples who are:
1. Padmapaada who wrote the work Panchapaadika which is an exposition of the contents of the Brahma Sutra Bhashya of Sankara.
2. Haastamalaka who wrote the short work Hastaamalakeeya which is said to have been commented upon by the Guru Adi Sankaracharya.
3. Totaka who wrote the Totakaastakam
4. Sureshwaracharya who is known as the Vartikakaara -- wrote Vartikas on Sankara's Brihadaranyaka and Taittiriya Upanishad bhashyas, Dakshinamurthy astakam of Sankara, Panchikaranam of Sankara & an independent Vedantic treatise called Naishkarmya Siddhi.
There are many acharyas who have been writing works on Advaita from centuries and even to date. The latest works of Advaita can be said to be works of Sacchidanandendra Saraswathi of Holenarsipur, M M Anantakrishna Sastri's works, Advaitamoda of Vasudeva Sastri Abhayankar, Vivekachoodamani commentary of Swami Chandrasekhara Bharathi of Sringeri and Soundarya Lahari commentary of Swami Chandrasekharendra Saraswathi of Kanchi.
Let us now try to see the basics of Advaita Vedanta.
The word Advaita means "one without second" or "no duality". As per Advaita, there is no two entities. There is only one real entity called as Brahman in the Upanishads. This one alone really exists. It is from this one that other things seem to have been created. The creation is only a seeming one and not a real one. The one entity is eternal and changeless. There cannot be any creation from the changeless entity. There is nothing apart from the one entity for that one entity to create other things. This is supported by Chandogya statement "sadeva soumya idam agre aaseet, ekam eva adviteeyam" --- the entity alone existed prior to creation.
Since before creation, that one entity alone existed -- therefore creation is not possible out of something other than that entity of Brahman. Brahman is also changeless as if it changes, it will become non-eternal. Since no change is possible from Brahman, Brahman cannot create anything out of itself. Thus the creation that we see which sruthi propounds as having come from Brahman is not a real one but just an empirical one. The creation is thus an adhyaaropa or superimposition on the ultimate reality of Brahman. This theory of apparent creation from Brahman is called Vivarta vaada. The best example of vivarta is that of seeing snake in the rope. There is no real snake in the rope created but snake is just an illusion apparently seen in the rope.
Similarly the world is never really created from Brahman but just seems to be created out of Brahman.
Brahman is of the nature of Existence, Consciousness and Bliss. Brahman has to be Existence because if it doesn't exist, it cannot be eternal. That Brahman is eternal has to be accepted on the basis of sruthi as well as yukthi. Yukthi shows that since we see something in the world -- that something needs to have a real creator or an apparent creation from a creator who is the substratum of the creation. Thus the substratum has to be existent and cannot be a void or shoonya. Thus Brahman is SAT or existence. If Brahman has to exist, it needs to experience its own existence or it needs to be conscious of its existence. Thus Brahman has to be of the nature of Consciousness. That which is existence and consciousness has to be blissful as well because when we are conscious of something, then we get bliss out of that thing. Thus that which is ever conscious of its own existence has to be blissful.
Thus Brahman is of the nature of Existence, Consciousness and Bliss.
Our own very nature or the "I" that pulsates in each one of us is Consciousness. Since this Consciousness is eternal and ever present -- it has to be one with Brahman. Because there is no duality in Brahman, thus there cannot be two consciousness but only one. Since there can be only one Consciousness, therefore we all are Brahman alone. "WE" here is only at the empirical level but the Consciousness underlying each one of us is the same only as there cannot be multiple Consciousness.
Thus we all are the reality of Brahman, one without a second.
Then why do we not get bliss of ourselves??? This is because we seem to have forgotten our nature of Brahman. This is called Avidya or Maya or ignorance. Ignorance cannot really be spoken about or explained because it is not a reality. A person can never forget his own existence but still he seems to have forgotten his nature of Brahman because else he would be blissful which he is not currently. Thus avidya is said to be anirvachaneeya or inexplicable.
This avidya is not a real entity but only seems to be present -- this seeming avidya vanishes when a person gets knowledge that "I am brahman" by contemplating on it continuously.
Thus avidya vanishes through scriptural knowledge that "I am brahman" and experiencing Brahman as the underlying substratum of everything that seems to be present.
Advaita is summarized by sankara in a half-verse thus
Brahma Satyam Jagan Mithyaa Jeevo Brahmaiva Na Parah
1. Brahman is the ultimate reality
2. The world is only an illusion in Brahman
3. Jeeva or individual existence is nothing but Brahman alone.
We will see into the intricate details of Advaita at a later time after going through the summary of each of the sub schools of Vedanta.
Humble salutations to all.