Adi Shankaracharya

Jagadguru

788–820 CE (traditional) · earlier dates argued by some historians Kaladi, Kerala

There is only one reality - Brahman - and you are not separate from it. The world of multiplicity is real but not ultimate.

The teaching

Brahman alone is real (sat); the world is mithya (apparent, not unreal); the individual self (jiva) is non-different from Brahman. Liberation comes through knowledge (jnana), not action; the obstacle is avidya (ignorance), the cure is the realisation of "Aham Brahmasmi". His method is uncompromising: every appearance, however dear, is investigated until only awareness remains.

Major works

Brahma Sutra Bhashya - commentary on Badarayana's Brahma Sutras (the foundational Vedanta text)
Bhashyas on the ten principal Upanishads
Bhagavad Gita Bhashya - line-by-line commentary
Vivekachudamani - "Crest-jewel of discrimination", standalone primer
Atma Bodha, Tattva Bodha, Aparoksha Anubhuti - short prakarana texts
Soundarya Lahari and Bhaja Govindam - devotional hymns (showing he honoured bhakti as preparation for jnana)

What he changed

Established the four mathas (monastic seats) at Sringeri, Dwarka, Puri, and Jyotirmath, each with a designated principal Veda and mahavakya
Codified Panchayatana Pooja - worship of five deities (Shiva, Vishnu, Devi, Surya, Ganesha) on a single altar - to harmonise sectarian rivalries
Revived Sanatana Dharma during a period of Buddhist and Jain dominance, defeating leading scholars of those schools in dialectical debate (most famously Mandana Mishra)
Defined the Dashanami Sampradaya - the ten orders of monastic renunciants

Living lineage today

The four Shankaracharya pithas (Sringeri, Dwarka, Puri, Jyotirmath/Badrinath) continue today, each headed by a sitting Shankaracharya. The Ramakrishna Order and the Chinmaya Mission stand within his lineage.