Sage Sankara founded his Advaitic Wisdom either on reason independent of Sruti or on Sruti confirmed by reason.+

Sage Sankara founded his Advaitic Wisdom either on reason independent of Sruti or on Sruti confirmed by reason."

Sage Sankara taught that it was only through direct knowledge of non-duality that one could be enlightened.

Sage Sankara’s opponents accused him of teaching Buddhism in the garb of Hinduism because his non-dualistic ideal was a bit radical to contemporary Hindu philosophy. 

However, it may be noted that while the Later Buddhists arrived at a changeless, deathless, absolute truth after their insightful understanding of the unreality of samsara, historically, Vedantins never liked this idea.

Although Advaita also proposes the theory of Maya, explaining the universe as a "trick of a magician", Sage Sankara and his followers see this as a consequence of their basic premise that Atman is real. Their idea of Maya emerges from their belief in the reality of Atman, rather than the other way around.

Sage Sankara was a peripatetic orthodox Hindu monk who traveled the length and breadth of India. The more enthusiastic followers of the Advaita tradition claim that he was chiefly responsible for "driving the Buddhists away". Historically, the decline of Buddhism in India is known to have taken place long after Sage Sankara or even Kumarila Bhatta (who, according to a legend, had "driven the Buddhists away" by defeating them in debates), sometime before the Muslim invasion into Afghanistan (earlier Gandhara).

Although today's followers of Advaita believe Sage Sankara argued against Buddhists in person, a historical source, the Madhaviya Shankara Vijayam, indicates that Sage Sankara sought debates with Mimamsa, Samkhya, Nyaya, Vaisheshika, and Yoga scholars as keenly as with any Buddhists. In fact, his arguments against the Buddhists are quite mild in the Upanishad Bhashyas, while they border on the acrimonious in the Brahma Sutra Bhashya.

The Vishistadvaita and Dvaita schools believe in an ultimately attributed Atman. They differ passionately with Advaita, and believe that his attriubuteless Atman is not different from the Buddhist Sunyata (wholeness or zeroness) — much to the dismay of the Advaita school. A careful study of the Buddhist Sunyata will show that it is in some ways metaphysically similar to Atman. Whether Sage Sankara agrees with the Buddhists is not very clear from his commentaries on the Upanishads. His arguments against Buddhism in the Brahma Sutra Bhashyas are more a representation of Vedantic traditional debate with Buddhists than a true representation of his own individual belief. 

Sage Sankara's commentary on the Manduka Upanishad, II, 1: This [the unreality of duality] is borne out by the Srutis ... But it is possible also to show the unreality of the objective world even from pure reasoning, and this second chapter is undertaken for that purpose.

Sage Sankara himself had often said that his philosophy was based on Sruti, or revealed scripture. This may be because Sage Sankara addressed the ordinary man, who finds security in the idea of causality and thus in the idea of God, nd Revelation is indispensable to prove the latter. He believed that those of superior intelligence have no need for this idea of divine causality, nd can, therefore, dispense with Sruti and arrive at the truth of Non-Dualism by pure reason. :~Santthosh Kumaar