Two?

svapne 'rthashunye srjati svashktyã

bhoktrãdivishvam mana eva sarvam/

tathaiva jãgratyapi no vishesha-

statsarvametanmanaso vijrmbhanam//

In dreams devoid of purpose, the mind of the dreamer creates the entire universe by its own power/

Thus, also in the waking state, there is no distinction; and all of this is an extension of the mind//

                                                                                            Shri Shankarãcãrya, Vivekacudamani, 170


The domination of the Vedas has persisted throughout history. However, there have been challenges and tributaries of thought. As an oral culture, the Aryans handed down their knowledge via the system of smriti (memory) and shruti (auricular transmission). Panditãh, (or in English "pundits" (experts)) of the Vedas would memorize large sections and in turn pass them along to the next generation, for thousands of years.

Shankara has come to be known as one of the progenitors of Advaita Vedanta, literally "the non-dualism of the end of the Vedas." This was the philosophical and spiritual innovation to end all philosophical and spiritual innovations. It was the Finnegans Wake of Indian thought, and Shankara's Vivekacudamani was a force to be reckoned with, keeping the professors and pundits busy for centuries.

The driving concept of Advaita, or non-dualism is pretty simple--the Atman, (aka, the soul or psyche) of the Universe is not distinct from the perceived individual Atman of "You" and "I." Simply put, there is no "You" nor "I." Those distinctions are products of a disillusioned mind, finding differences rather than connections. Synthetic versus analytic.

Shankara's philosophy, however, is not for the meek, nor is it for everyone, yet it is for everyone, reminding one of the sub-title to Nietzsche's Also Sprach Zarathustra: ein Buch für Alle und Keinen, a book for all and none alike. This was no easy lifting, and Shankara makes it quite clear that only a student steeped in the Vedas, Upanishads, and Commentaries, combined with a Yoga of the mind and body, complemented by a proper guru, or teacher, can approach this thought successfully. (NB: being a brahmin, Shankara adds that one must also be a male, sign of the times.)

The highest revelation that the Atman, the soul can obtain is to see that the individual is inextricably part of the whole, it is the whole. There are no parts. To become "one with the universe" is likewise a falsehood, as there was never a sundering, only an illusion of it.

Shankara's Advaita Vedanta has come down as one of the most challenging systems of thought in all of philosophy, with proponents and opponents both in the East and the West with most notably and most recently Shri Aurobindo of Kolkutta taking on the role of both.