The Vedas are the oldest sacred writings of all of the world’s major religions. Most scholars believe that the Vedas were transmitted orally for hundreds if not thousands of years before they were committed to writing.

When written down, they were recorded in archaic Sanskrit and organized into collections called Samhitas. There are several versions of the Vedas in different parts of India. Internal evidence in the Vedas suggests that they were first composed to serve as rituals at the performance of sacrifices.

The Aryans who moved into the Indus Valley region around 1500 b.c.e. produced the Vedas. They were Indo-European-speaking peoples from the steppes of Central Asia, whose language when committed to writing became Sanskrit.

The Aryan invaders (or possibly immigrants) moved through what are today areas of Iran and Afghanistan before crossing the Hindu Kush through the Khyber Pass or other mountain canyons. There may have been five tribes of Aryans who called themselves arya, which means "noble" or "kinsman" in Sanskrit.

They conquered the original residents or pushed them southward as they moved down the Indus River valley and eventually spread across much of the north Indian plain. The Aryans brought their own religion to India. The gods (devas) and goddesses of the nomadic cattle herding Aryans were usually primal forces of nature. Their Vedic religion practiced rituals that used songs and sacrifices.

The title Veda(s) comes from a Sanskrit word, veda, which means "knowledge" or "sacred teachings". They were the heard revelations (shruti) of holy men (rishis). The rishis did not "create" the Vedas, but "heard" the Brahma speak them and recorded them.

The Vedasamhitas are a huge body of materials, six times the length of the Bible. There are four Vedas: the Rig-Veda, the Sama-Veda, Yajur-Veda, and the Atharva-Veda. The Rig-Veda (hymn knowledge) is a collection of more than 1,200 hymns.

A rig is the Sanskrit word for "hymn", and each rig is addressed to a single god or goddess. The oldest of the rigs date from well before the Aryan migrations into the Indus Valley. They were addressed to the sky god, Dyaus Pitar, who can be identified with the classical Olympian god Zeus Pater or the Latin Deus (Ju)pitar.

In a subsequent stage in the development of the Vedas the old gods faded and were replaced by new gods. These newer gods include Indra, the sky god and the king of the gods. Among the newer Aryan gods included in the Vedas are Agni, the Vedic god of fi re, and Soma, the god of a hallucinogenic drug.

The hymns in the Rig-Veda developed during the period of 1500–1200 b.c.e. They reached their final form around 1200 b.c.e. and were used as part of the cult of Soma. They were also used at the sacrifi ces used to extol the personified deities of fire (Agni), the sun (Surya and Savitr), the dawn (Usas), the storms (Maruts), war and raid (Indra), honor (Mitra), divine authority (Varuna), and creation (Indra and Visnu).

A priest would chant the rigs of the Rig-Veda during the performance of a sacrifice. The gods that are praised in the Rig-Veda hymns are addressed individually, and each is praised above all the other deities to create a form of henotheism.

There is first an invocation of the deity. Then the deity is presented with a petition. Then the deity, a god or goddess, such as Varuna, Mitra, Aditi (mother of the gods), and Uma (the dawn) is given praises that recount the deeds of the deity. The final part of the form of the rig is a summary restatement of the worshippers’ request.

The themes of the rigs in the Rig-Vedas include creation, death, the elements of sacrifice, the horse sacrifice, gods of the storm, solar gods, and to sky and earth gods. In addition, rigs may be dedicated to Agni, to Soma, to Indra, to Varuna, or to Rudra and Visnu.

The rigs that are dedicated to Indra tell of things such as the birth and childhood deeds of Indra. Some rigs were written about speech used to sing of Indra’s origin. Other rigs express delight in the drawing of the bow to strike those who hate prayer. Others rigs were used during the investiture of a new king.

The Sama-Veda (chant knowledge) is a collection of chants and melodies (saman) used in sacrifices. It was composed after the Rig-Veda was completed. Most of the words in the Sama-Veda were taken from the Rig-Veda. The lines of the Rig-Veda quoted in the Sama-Veda were to be sung to fi xed melodies making them in effect mantras.

The melodies used to sing the Sama-Veda materials were not captured in the text but are passed on from a singing priest to his disciples. The priests who sang the Sama-Veda were different from those who used the Rig-Veda. Proper lyrics and music are essential to the success of the rite.

The Yajur-Veda (ceremonial knowledge) was also written after the Rig-Veda. Most of it is a collection of prose sacrificial formulas (yujus), used by the presiding priest in a sacrifi ce. More specifically they are directions for conducting the sacrifice. The Rig-Veda, Sama-Veda, and the Yajur-Veda are today known in Hinduism as the "threefold Veda" (trayi-vidya).

These reflect the religious life of the priestly group. The Atharva-Veda (knowledge from the teacher Atharva) differs greatly from the other three. It is composed of spells, prayers, curses, and charms that are practical in nature. They include prayers for warding off snakes or sickness.

When sacrifices were performed the priest would sing or chant materials from the Vedas that were appropriate to the type of sacrifice. A different priest would handle each part of a sacrifice. There were at least three groups of priests using the Rig-Veda at the sacrifices.

The chief priest (hotr) would take material for his changes from the Rig-Veda. The priest responsible for chanting the sacred formulas (mantras) was the adhvaryu. A third group of priests, the chanters (udgatr), would chant melodic recitations that were linked to the Rig-Veda.

Over time additional materials came to be attached to each of the four Vedas. Most commonly the Vedas are viewed as including the Brahmanas, the Arayankas, and the Upanishads. The Brahmanas (Brahman books) were the name for the priests, or Brahmans.

They are the manuals for sacrifice. They discussed in detail rituals, proper time and place for ceremonies, the preparation of the ground, ritual objectives, purification rites, and other matters.

Ascetic holy men who went into the forests to meditate composed the Arayankas (forest books). These books interpreted the Vedas in a nonliteral and symbolic ways. They contain speculations on sacrifice, especially the sacrificial fire and the New Year festival.

The Upanishads (Sittings near a teacher) were the last to be composed and added to the Vedic collections. Several theories have been proposed to explain the origin of the name Upanishad.

The belief is that they were composed as disciples sat near a guiding teacher. With the disciple sitting near the priest, both of them would experience spiritual enlightenment. They would experience the spiritual reality that is the unifying reality underlying all of the separate realities of the world.

Most of the Upanishads are dialogic. The prose Upanishads, like the Chandogya, Birhadaranyaka, Taittiriya and the Kena are probably earlier than the poetic ones such as Katha and Mandukya. The emphasis on spiritual experience suggests a shift in Vedic religion from the view that only hereditary priests can be religious masters to the view that both priests and nonpriests can experience spiritual realities.

The Upanishads are the most philosophical of the Vedas and are concerned with ultimate philosophical truth. They number about 100. Their concerns are to record insights into internal and external reality.