The beginnings of Indian Philosophy take us very far back to about the middle of the second millennium before christ. The speculative activity began so early was continued till a century or two ago so that the history that is narrated in the following pages covers a period of over thirty centuries. During this long period Indian thought development was practically unaffacted by outside influence and the extent as well as importance of its achievements will be evident when it is mentioned that it has developed several systems of philosophy besides creating a great national religion.