After examining the five great systems of Philosophy separately, they combined them in sets of two and three according to their affinity and range, and constructed on them their four great systems of Religion – Vaishnavism, Saivism, Buddhism, and Jainism, with Sakti worship as a connecting link between all. An account of this has been given earlier. All the ancient Sacred Books of the Hindus are an attempt to embody the truths of Science in systems of Philosophy and Religion in different forms, referring them to the daily life of the average man. The gods of the Vedas personify the five great creative energies of life, separately and together, at different stages of their evolution; the Brahmanas express the same idea in terms of creative and selfless Action or Sacrifice: the Upanishads and the systems of Philosophy deal with the same subject more directly; and the Puranas and the Epics of Ramayana and Mahabharata represent them in Story form. 

In the Bhagavad Gita, the most sacred book for the Hindu way of life, Bhagwan Krishna is quoted as saying "I am the great epic among the stories," a "wink" at the manner of education prevalent in Idnia at the time. These epics cover the whole range of human thought, from Physics to Metaphysics, from pure Monism of God to qualified Monism, Dualism, Agnosticism, and Atheism; and from the Soul of Man to his Buddhi, Mind, and the Senses of Knowledge and Action. Indeed, it would be difficult to conceive of anything outside this range, and this would explain the statement in the Mahabharata, "That which is in it, is elsewhere. That which does not occur here, occurs nowhere else." 

But this was not a mere theory or abstract speculation; it was intended to bear on the life and conduct of the average man. All of us are not at the same stage of evolution and development. There are five great creative energies in Man, from the Soul to the Senses, and each of us has more of the one or the other specially defined. Many of us are at the stage of the Senses and see all things in their light; others are at the Mind stage and can think; some, however, are at the Buddhi stage, with doubts resolved and mind at peace; while a few are at the Soul stage, ever acting in a spirit of Sacrifice, undisturbed by change, and always happy at heart. Each of us can understand the problem of life in the light of his own character and the stage of his evolution and development; and the five systems of Philosophy and their corresponding Religions, bearing as they do on the five great creative energies of life, provide for each individual an ideal and a goal according to his peculiar point of view. 

The ultimate Truth is indeed one, conceived in the light of one God, one Nature, one Soul, and one Law of life, viz., Sacrifice; but we have to rise by stages to grasp this Truth. This is the peculiarly sublime character of the ancient systems of thought, giving to each individual an ideal according to his stage of development and yet comprehending the whole. They are not complete or rival systems, as some imagine, but different stages and different landmarks in our study of the problem of life, each leading to the other, until we attain to the ultimate Truth, and view all things in the light of God and the Soul. That is Vedanta, the essence of all Knowledge, even as the word implies, when we see all life as perpetual Sacrifice, and the whole universe eternally happy and good.