The aim of the Vedic fire sacrifice and of Aryan religion itself was to ensure well-being and prosperity in this life. The early Vedas contained little evidence of sustained thought about human destiny beyond this life – or an afterlife. The doctrines most associated with Hinduism, such as the cycle of reincarnation driven by karma and the liberation from bondage through yoga discipline, were reflected a thousand years later in the more recent Vedic literature called the Upanishads.
Of the four Vedas, the Rig Veda is the most important and foundational. The most popular God of the Rig Veda is the expansive and dynamic Indra. He is said to have surpassed the other gods in power as soon as he was born, and he is credited with having created the world by slaying a cosmic serpent and bust releasing the life-giving monsoon bringing waters that help the Aryans overcome the non-Aryan people they met. Because of his role in the important fire sacrifice, Agni, the god of fire is perhaps second only to Indra in popularity with over 1000 hymns dedicated to him in the Vedas. The entire ninth book of the Rig Veda is addressed to Soma, the God who inhabits the mysterious psychotropic beverage, said to be the food of the gods. Soma probably ranks behind only Indra and Agni in Vedic popularity.
The early Vedic religion was polytheistic, the notion of an all-encompassing metaphysical unity, God, so important in the later Upanishads made an occasional appearance. Quite a different Vedic creation hymn conceives the world's origin as a divine being’s, Purusha’s, self-sacrifice. In this creation story, we not only have the seeds of the mythic rationale for the fire sacrifice, but the importance of the priestly reenactment of the sacrifice that sustains it. Further, in the Rig Veda there is reference to the four social groups that have constituted the Indian “caste system” for thousands of years. The Aryan social structure featured a broad occupational division of clans into a 1) priestly caste, the Brahmins; 2) a military and political caste, the Kshatriyas; 3) an artistan caste, the Vaishyas; and 4) the non-Aryan populations were incorporated as a fourth class of laborers, the Shudras, to serve the other three.
In the Upanishads we first see the pan-Indian diagnosis of the human condition as trapped in a ceaseless round of death and rebirth, Samsara, due to the actions and the consequences of actions, Karma, performed in ignorance of the divine ground of all life, Brahman. Also introduced in the Upanishads is the remedy for liberation of the soul from this confining ignorance through each individual's realization of his inner spiritual nature, the universal self or Othman, which is none other than Brahman.
Another form of Vedic literature are the Brahmanas, which are clerical compositions mainly explaining the Vedic sacrificial rituals and their underlying symbolism. The oldest of the Brahmanas is the Shatapatha Brahmana of the Yajur Veda, which dates to approximately 900 B.C.E.
The Mahabharata, or the great story of the Bharatas, is an account of the origins, the course and the results of a great war between two clans, the Pandavas and their cousins, the evil sons of Dhritarashtra. The Bharatas were an Aryan tribal group who raided and plundered other villages over several generations. The work is a compilation of various texts and traditions gathered over hundreds of years from about 540 B.C.E. to the third century C. E. One can assume that Vyasa, the legendary author, is probably fictional or mythical because he has been credited with writing most of India's sacred literature including the Vedas and the 18 Puranas. Such a feat would encompass a life of several thousand years. 
The Mahabharata and The Ramayana
Along with the Mahabharata, the Ramayana recounts the life of Rama and is one of the two major national epics of Indian literature attributed to the public and sage Valmiki sometime during the first century B.C.E. The Ramayana is a story of tragic love between Rama and Sita, but it is also an epic dealing with the asceticism so typical for India.
Recognized as one of the greatest works of world literature, the Bhagavad-Gita is contained within the long epic poem, the Mahabharata. The Bhagavad-Gita has been called the most important and influential of Hindu scriptures. Indeed it is the most popular book in Hindu religious literature and one that most Hindus regard as containing the essence of the Vedas and the Upanishads. The message of the Bhagavad-Gita is that each human being has but one ultimate purpose: to realize the eternal self within and thus to know the joy of union with God. Traditionally, followers sought union with God in retreat from the world, but without omitting that option the gate to enlightnment, teaches that it may be attained in the midst of the world through non-attached action, bhakti, in the context of devotion to God.
The story of the Bhagavad-Gita opens on the battlefield where the two vast and powerful armies stand. There is no doubt that there is going to be a bloodbath and a civil war among blood relatives. The noble warrior, Arjuna, was profoundly disturbed by the concept of war, but it was his role to lead his clan, the Pandavas, into battle. The tormented Arjuna prays for help from the Lord Krishna, who in human form stands beside him in his chariot. Troubled by his double duty as a warrior to protect his family from evil aggression and the spiritual duty of nonviolence, Arjuna confesses his confusion to Lord Krishna. A lengthy conversation between the two follows whereupon Arjuna resolves his dilemma by choosing the path of dispassionate action. Dispassionate action, or Karma Yoga, is perhaps the central teaching of the Bhagavad-Gita. Aside from its religious import to Hindus, the simplicity and spirituality of the Bhagavad-Gita has appealed to readers of many cultures, and many times.
Finally, a category of Indian sacred literature available to the common people and not exclusively in the domain of the priests, are the Puranas. Most of the Puranas were composed during or after the fourth century C. E., but they often contain older legends and traditions that reveal the beliefs and practices of early folk religion. Traditionally, there are 18 principal Puranas and an unspecified number of minor ones. The texts were generally subdivided into three classes, according to the particular deity of the Hindu trinity that they most exalt: Brahma, Vishnu, or Shiva. To this day, the main schools of Hindu teaching follow the same format with allegiance to one of the three deities.
Fourteen hundred years after the Aryans sowed the seeds of Hindu faith in the Indian sub-continent, Buddhism sprang from Hindu roots and spread throughout the Far East. Through cross-cultural exchange, elements of Hinduism are evident in all religions that emanate from the Near East.
-  Novak, Philip, The World’s Wisdom, Harper Collins, San Francisco, 1994, p. 1
-  Novak, Philip, The World’s Wisdom, p. 4
-  Novak, Philip, The World’s Wisdom, p. 7
-  Camphausen, Rufus, The Divine Library, Inner Traditions international, Vermont, 1992, p. 56
-  Camphausen, Rufus, The Divine Library, Inner Traditions international, Vermont, 1992, p. 71
-  Koller, John, The Indian Way, Macmillan, New York, 1982, p. 188
-  Novak, Philip, The World’s Wisdom, p. 24
-  Camphausen, Rufus, The Divine Library, Inner Traditions international, Vermont, 1992, p. 113