Brahman, according to the Upanishads and Shankara, the major exponent of the philosophy of the Upanishads known as Advaita, is not a metaphysical postulate meant to explain what is empirically experienced or the word. Brahman is absolutely real and is the inner reality or essence or self of all that is there, including one s self. Therefore it is known directly and immediately as the real or true nature of one s self. In the context of human reality Brahman is known as Atman, the true reality or nature of one s self. Direct and unmediated experience or realization of Brahman or brahmanubhava is the consummation of man s spiritual life as well as the supreme fulfilment of human existence. This is an attempt to understand comprehensively, and in depth the meaning and significance of brahmanubhava as presented and discussed by Shankara in his commentaries on the Upanishads, Brama-Sutras and the Bhagavad-Gita, and in his other minor works, like Vivekacudamani, Aparokshanubhuti and Upadesha-Sahasri. Shankara is also known for his logical acumen and analytical approach to problems of philosophy. However, the mystical dimension of his philosophy which is also the reason for the lasting relevance and significance of his philosophy has not received the attention it deserves. May be this is the first of its kind in understanding and presenting systematically the Advaitic mysticism of Shankara in all its aspects. It is entirely based on the works of Shankara. An attempt is also made in this book to understand the significance of Advaitic mysticism of Shankara in the light of its comparison with that of St. John of the Cross and Jalalu d-Din Rumi, classical representatives of Christian and Islamic mysticisms.