The Rig Veda is the oldest of the Vedas. All the other Vedas are based upon it and consist to a large degree of various hymns from it. It consists of a thousand such hymns of different seers, each hymn averaging around ten verses. The Rig Veda is the oldest book in Sanskrit or any Indo-European language. Its date is debatable. Many great Yogis and scholars who have understood the astronomical references in the hymns, date the Rig Veda as before 4000 B.C., perhaps as early as 12,000. Modern western scholars tend to date it around 1500 B.C., though recent archeological finds in India (like Dwaraka) now appear to require a much earlier date. While the term Vedic is often given to any layer of the Vedic teachings including the Bhagavad Gita, technically it applies primarily to the Rig Veda.
The Rig Veda is the book of Mantra. It contains the oldest form of all the Sanskrit mantras. It is built around a science of sound which comprehends the meaning and power of each letter. Most aspects of Vedic science like the practice of yoga, meditation, mantra and Ayurveda can be found in the Rig Veda and still use many terms that come from it. While originally several different versions or rescensions of the Rig Veda were said to exist, only one remains. Its form has been structured in several different ways to guarantee its authenticity and proper preservation through time.
The Rig Veda consists of the hymns to various aspects of the Divine as seen by various seers, called the "rishis". There are seven primary seers, identified not only in India but also in Persia and China with the seven stars of the Big Dipper. Their names are Atri, Kanwa, Vasishta, Vishwamitra, Jamadagni, Gotama and Bharadvaja, but they appear even in the hymns of these sages and may refer to an earlier group. They relate to the guiding lights of the seven chakras.
The main family of the seers was called the Angirasas (a term related to the Greek Angelos and our English word angel). The seven seers are all Angirasas and their families or lineages are a diversification of this one original line. The foremost of the Angirasas was Brihaspati, identified with the planet Jupiter. Other important seer families were the Bhrigus (associated with Venus) and the Ribhus. Some Vedic Gods may have also been families of the seers, including the Maruts, the Adityas and the Ashwins. Each of the seven seer families still has many descendants in India and elsewhere. They were said to be the progenitors of the human race. The head of each of the seer families was like a Tulku and took many births or passed on his teaching to many successors who bore his name. Hence Vedic and Puranic literature is filled with many Vasishtas, Vishwamitras, etc.
The Rig Veda is composed of ten books (called mandalas in Sanskrit). Seven of the books each relate primarily to one great seer and the family he belongs to; the second book belongs to Gritsamada and his family, the Bhrigus; the third relates to Vishwamitra and his family; the fourth to Vamadeva and the Gotama family; the fifth to Atri and his family; the sixth to Bharadvaja and his family; the seventh to Vasishta and his family; and the eighth to the Kanwas. The first book is a collection of hymns from seers of different families, mainly earlier ones. The tenth book is a collection of various earlier and later hymns. The ninth book is the collection of Soma hymns mainly from the Bhrigus and Angirasas. It is largely outside of and earlier than the family books. Hence the Soma book is the oldest of them all.
Each hymn is given to a certain deity (devata). The main deities are Indra, Agni, Soma and Surya. The Vedic Gods have many different levels of meaning. They represent an intuitive symbology which transcends the limited constructs of the intellectual mind. Indra is the God of Prana or the awakened life-force. He represents the perceiver or the consciousness of the seer. He is the young warrior wielding the thunderbolt or vajra, which destroys the demons or powers of falsehood. Agni is the God of consciousness, awareness and mindfulness. His symbol is the sacred fire. The offerings to him outwardly symbolize our inward giving to the higher awareness within us. Soma is the mystic plant that yields the nectar of immortality. He is also the Moon and the lord of the waters. He symbolizes bliss, Ananda. Surya is the Sun which is the visible face and presence of the Deity. He symbolizes the enlightened mind and creative intelligence. He is the Divine creator and transformer.
Other important deities are Varuna, the lord of the cosmic ocean and the Divine judge; Mitra the Divine friend and lord of compassion and Savitar, the Sun God of creative intelligence. Goddesses are Usha, the Goddess of the Dawn or spiritual aspiration; Saraswati, the Goddess of the Divine Word, of wisdom and inspiration; Aditi the Goddess of Infinite Oneness and Wholeness; and Apas, the Cosmic Waters. Moreover each of the Gods has his consort, like Indra and Indrani, Varuna and Varunani. Collective deities exist like the Adityas, the solar deities, the Maruts or Rudras, Gods of the storm, the Ribhus or Divine craftsmen and the Vishvedevas, literally the universal Gods who symbolize the unity of all the Gods.
The trinity of later Hinduism, Brahma the creator, Vishnu the maintainer and Shiva the destroyer is present in the Rig Veda but behind the scenes. Brahma is Brihaspati, also called Brahmanaspati, the priest of the Gods. Vishnu is an important form of the Sun God and later all forms of the Sun God were merged into him. Shiva is present as Rudra, the seldom invoked but very much respected and feared father of all the Gods.
Each God or Goddess represents certain Divine qualities. They are present as the guiding forces both in nature and in the human psyche. Hence they are largely a personification of ideas, of the truth perceptions, the great archetypes of the Divine Mind. For example, the God Mitra, whose name literally means friend, stands for friendship and its importance in life as a divine or spiritual quality.
Each God or Goddess can be any or all the Gods. The concepts of monotheism, polytheism, pantheism and monism are all woven together in the Vedic vision of totality. The Divine is seen as both One and Many without contraction. The Divine is all the universe and all the cosmic powers which rule it but it also transcends the world. Such a wholistic view of the world was quite confusing to the scholars who first translated the Vedas, but perhaps today we can appreciate in better in light of our larger view of the world and the psyche.