Written sometime between 1904 and 1906, during the latter part of his stay in Baroda, The Philosophy of the Upanishads, though left incomplete by the author, represents an early stage of Sri Aurobindo's thinking on the most important scriptures of Vedanta philosophy. In the Preface he comments that not only is the philosophy of the Upanishads at the base of all Indian religion and morals, and of Hindu politics, legislation, and society, but it has also profoundly influenced Western thought in both subtle and evident ways.
Sri Aurobindo (Bengali: শ্রী অরবিন্দ Sri Ôrobindo) was an Indian nationalist and freedom fighter, major Indian English poet, philosopher, and yogi. He joined the movement for India's freedom from British rule and for a duration (1905–10), became one of its most important leaders, before turning to developing his own vision and philosophy of human progress and spiritual evolution.
The central theme of Sri Aurobindo's vision is the evolution of life into a "life divine". In his own words: "Man is a transitional being. He is not final. The step from man to superman is the next approaching achievement in the earth evolution. It is inevitable because it is at once the intention of the inner spirit and the logic of Nature's process."
The book starts on an interesting note. It appears to provide the crux of Vedanta. But loses flow in last 2 chapters. Sri aurabindo has left this book incomplete.