Swami Sivananda 
The Bhagavad Gita 

The Bhagavadgita is one phase of the Tripod of Indian philosophy and culture, the other two phases being the Upanishads and the Brahmasutras. While the Upanishads lay the foundation of the loftiest reach possible for humanity and the Brahmasutras logically elucidate the intricate issues involved in the Upanishads, the Bhagavadgita blends together the Transcendent and the Immanent features of the Ultimate Reality, bringing together into an integrated whole knowledge and action, the inner and the outer, the individual and the society, man and God, all which are portrayed as facets of a Universal Operation, presenting entire life and all life as a perfectly complete organic wholeness, leaving nothing unsaid and attempting to solve every problem in life.