Adi Shankara, a Hindu philsospher of the Advaita Vedanta school, wrote many works in his life-time of thirty two years; however, many works thought to be of his authorship are debated and questioned as to their authorship today. His works deal with logically establishing the doctrine of Advaita Vedanta as he saw it in the Upanishads. He formulates the doctrine of Advaita Vedanta by validating his arguments on the basis of quotations from the Vedas and other Hindu scriptures. He gives a high priority to svānubhava (personal experience) of the student. Also, a large portion of his works is polemical in nature. He directs his polemics mostly against the Sankhya, Bauddha, Jaina, Vaisheshika and other non-vedantic Hindu philosophies.
Traditionally, his works are classified under Bhāshya (commentary), Prakarana gratha (philosophical treatise) and Stotra (devotional hymn). The commentaries serve to provide a consistent interpretation of the scriptural texts from the perspective of Advaita Vedanta. The philosophical treatises provide various methodologies to the student to understand the doctrine. The devotional hymns are rich in poetry and piety, serving to highlight the helplessness of the devotee and the glory of the deity. A partial list of his works is given below.


Upadesa Sahasri (upadEshasAhasri) is a philosophical treatise by sri Adi Shankaracharya , in which he explains ‘a method of teaching the means to liberation for the benefit of those aspirants after liberation who are desirous (of this teaching) and are possessed of faith (in it)’ . Upadesa Sahasri literally means, a thousand teachings, which Adi shankara wrote parly in prose and partly in verses.

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The Bṛhadāraṇyaka Upanishad is believed to be one of the older, “primary” (mukhya) Upanishads. It is contained within the Shatapatha Brahmana, and its status as an independent Upanishad may be considered a secondary extraction of a portion of the Brahmana text. This makes it one of the oldest (if not the oldest) texts of the Upanishad corpus, possibly dating to as early as the 9th century BCE. It is associated with the White Yajurveda. It figures as number 10 in the Muktika canon of 108 Upanishads and was notably commented upon by Adi Shankara.

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To answer simply, Advaita is not based on any single soul – there is no soul and not-soul at that ultimate understanding – there is only one non-dual sat chit and ananda. Existence-consciousness-ananda cannot be divided. If one sees divisions they are only apparent and not real. If one takes the apparent as real, then all others factors become as real.

Jiiva (soul) itself is a notion and when that notion is taken as real – all other problems become as real as jiiva. Hence reincarnation and transmigration of soul are all real in that frame of reference.

Look at this way: gold, iron and copper look different if these difference as taken as real. They can exist in different forms – now as ring, now as bangle, now as chain, now as bracelet – gold undergoing transmigration or reincarnation into different forms.

If one understands that all are nothing but electrons, protons, neutrons etc., then from that perspective gold, iron, copper are just bunches of electrons, protons and neutrons – which themselves are nothing but energy-states.

I can understand as a scientist they are all one – yet I can transact in the world taking gold as different from iron and copper. Transactions are done at one level while understanding is at the ultimate level – there is no confusion if one understands correctly. I know that the sun neither rises nor sets but I can still appreciate the beauty of sunrise and sunset.

That is advaita in spite of dvaita – that is no incarnation in spite of reincarnation. Karma (action) is at the transactional level. At the absolute level I realize that I am never a kartRRi (doer). That is Advaita. Advaita in spite of dvaita.

Source: http://www.advaita.org.uk/discourses/teachers/reincarnation_sada.htm

More Info: Advaita Vedanta of Shankaracharya

The Muṇḍaka Upanishad is one of the older, “primary” (mukhya) Upanishads commented upon by Adi Shankara. It is associated with the Atharvaveda. It figures as number 5 in the Muktika canon of 108 Upanishads.

This Upanishad divides all knowledge into two categories. The knowledge that leads to Self Realization is called Para Vidya or Divine Knowledge and everything else is called Apara Vidya or Knowledge of Material world. It is the first text to mention the six disciplines of Vedanga.

More Info: Mundaka Upanishad