One may wonder why the Bhagavad Gita came into existence when we already had such scriptures as the Vedas and Upanishads. The great Vedantic sage Shankara explained, "The Vedic dharma was practiced over a long time. But eventually discrimination and wisdom declined. Unrighteousness became more predominant than righteousness." The Vedas are the source of all streams of Indian philosophy and psychology, and the Upanishads are the later parts of the Vedas. With the decline of discrimination and wisdom, it became difficult for those who were not scholars to understand the teachings of the Vedas and Upanishads. So it was necessary to restate these teachings in a way that could be appreciated and assimilated by all. The Bhagavad Gita contains in condensed form all the philosophical and psychological wisdom of the Upanishads.