Sri Nisargadatta Maharaj

The seeker is he who is in search of himself. Give up all questions except one: ‘Who am I?’ After all, the only fact you are sure of is that you are. The ‘I am’ is certain. The ‘I am this’ is not. Struggle to find out what you are in reality.
To know what you are, you must first investigate and know what you are not.
Discover all that you are not — body, feelings thoughts, time, space, this or that — nothing, concrete or abstract, which you perceive can be you. The very act of perceiving shows that you are not what you perceive.
The clearer you understand on the level of mind you can be described in negative terms only, the quicker will you come to the end of your search and realize that you are the limitless being.
(Nisargadatta in “I am That”)

Maharaj Nisargadatta (1897–1981) was a Bombay (Mumbai) merchant and householder, whose Advaita Vedanta teachings and Jnana Yoga practices drew him a large following. His conversations, recorded by disciples and translated into English, ensured that his ideas would continue to spread after his death.
Born in Bombay in March 1897, Maruti (his birth name) was raised on a small family farm near Kandalgaon in Maharashtra. As a boy he became familiar with spiritual topics by listening to his parents discuss the spiritual life with a BRAHMIN friend, Vishnu Haribha Gore. When his father died in 1915, Maruti and his elder brother became responsible for supporting the family. They left home to seek employment in Bombay. Here, Maruti opened a shop selling bidis, handmade cigarettes. He became prosperous in the trade and established several more shops across Bombay. In 1924, Maruti married Sumatibai, and they later became the parents of a son and three daughters.
At age 34, Maruti began to seek answers to universal questions. His friend took him to Sri Siddharameshwar Maharaj, a teacher in Bombay in the Navnath Sampradaya, who gave Maruti a mantra and instructions on meditation. Maruti quickly developed a practice, giving attention to nothing else than the sense of “I am.” Soon, Maruti began to have visions and to experience trance states. Between 1933 and 1936, he experienced Self-realization and reported that he lived in full awareness of the transcendent reality. He named himself Nisargadatta (One Given True Being).
After Sri Siddharameshwar’s death in 1936, Nisargadatta left his family and business to live the renounced life of a sadhu, a wandering monk who owns nothing and begs for food, in the Himalayas. His journey was short-lived, after a fellow disciple convinced him that his spiritual intentions would be more fruitful at home. Returning to Bombay he found his business in shambles. He reestablished one bidi shop, which sustained him and his family. Nisargadatta spent the remainder of his life tending his business and devoting himself to a strict discipline of daily observances and veneration of his guru. He meditated and discussed his master’s teachings with all who visited his bidi shop and did not visit saints or temples. As he began to speak to others, larger and larger groups of inquirers and students went to his shop to learn from his eloquence and wisdom.
Nisargadatta’s teachings are based on Jnana Yoga and Advaita Vedanta, a non-dualistic philosophy. His teachings emphasize the individual’s direct experience with the eternal in the here and now. His typical recommendation to new students was to practice with discipline and follow the same instruction provided to him, which fostered Self-realization. Nisargadatta encouraged seekers to draw attention to “I am.” In doing so, he asserted that the practitioner’s mind would soon gain self-realization in thought and feeling. Nisargadatta died in Bombay on September 8, 1981.
Ramesh S. Balsekar became one of Nisargadatta’s closest disciples. Balsekar, a graduate of London University and retired banker, met Sri Nisargadatta in 1970. He became entrusted with recording the conversations of Nisargadatta, the guru’s primary method of teaching. Many of these were later published in the book I Am That (1972), which has become a classical treatise on how one person can realize the non-dual reality outside time and space. As more Westerners encountered Maharaj they furthered his teachings by translating his conversations into English, publishing them throughout North America and Europe.
After Nisargadatta Maharaj’s death, Balsekar continued his guru’s teachings and established the Advaita Fellowship in 1987. Since that time he has made annual visits to America and has become esteemed as a teacher of Advaita Vedanta. The fellowship has its headquarters in Bombay (Mumbai), India, and in Redondo Beach, California.
(Encyclopedia of Hinduism)

A website devoted to Sri Nisargadatta Maharaj