This book serves as an introduction to the six systems of Hindu philosophy. Though these six systems are different in their approaches to the truth, they are unanimous as far as the final goal of humankind is concerned, which is, total eradication of suffering and attainment of state of eternal peace.
The book one must read to learn natural sciences is the book of nature. The book from which to learn religion is your own mind and heart.
-Swami Vivekananda