The Yajur Veda, the Sama Veda, and the Atharva Veda
The Rig Veda is the most important, but the other three Vedas are also significant. Each of the Vedic books is subdivided into four parts. Each contains a section of hymns to the gods, which recall the period when statements about the gods were memorized, chanted, and passed on from one generation to another; ritual instructions (Brahmanas), in which worshipers are given instructions about how to perform their sacrifices; the so-called Forest Treatises (Aranyakas), which give instructions to hermits in their religious pursuits; and the Upanishads, composed of philosophical materials.
Again, it is believed that the Vedas are revealed to the sages by God. The other possibility is that the Vedas revealed themselves to the seers or mantradrasta of the hymns. The Vedas were compiled by Vyasa Krishma Dwaipayana around the time of the Lord Krishna, around 1500
The Yajur Veda
The second book is the Yajur Veda, known as the Veda of Sacrificial Texts, a collection of sacrificial rites. It is also sometimes called a book of rituals. Simply put, it is a liturgical collection including the materials to be recited during sacrifices to the gods.
The Yajur Veda serves as a practical guidebook for the priests who execute sacrificial acts, simultaneously muttering the prose prayers and the sacrificial formulas (yajus). It is similar to ancient Egypt's Book of the Dead. There are no less than six complete recensions of the Yajur Veda — Madyan-dina, Kanva, Taittiriya, Kathaka, Maitrayani, and Kapishthala.
The Yajur Veda inspires humans to walk on the path of karma (deeds), so it is also called Karma Veda. It comprises hymns taken from the Rig Veda and adds explanatory notes in prose form. It contains fifty chapters each, which are subdivided into kandikas, or paragraphs, numbering 1,975 mantras.
The contents of the Vedas include the Principle of Dharma (ethics or duties), which are closely associated with the Principle of Karma — duty in life (action and subsequent reaction) according to one's caste for the betterment of society — and the principle of samsara (the continuing cycle of birth, life, death, and rebirth).
The Sama Veda
The third book, the Sama Veda, is also known as The Veda of Chants or Book of Songs. It contains the required melodies and chants recited by priests for special sacrifices. It is a collection of spiritual hymns, used as musical notes, which were almost completely drawn from the Rig Veda and have no distinctive lessons of their own. One Vedic scholar said that if the Rig Veda is the word, Sama Veda is the song or the meaning; if Rig Veda is the knowledge, Sama Veda is its realization; if Rig Veda is the wife, the Sama Veda is her husband.
The Sama Veda resembles the Rig Veda. Most of its mantras are taken from the Rig Veda, but the order is modified for chanting. It is divided into two books called ankas. It has twenty-one chapters and contains 1,875 mantras. These mantras are addressed to Agni, Indra, and Sama.
The Atharva Veda
The Atharva Veda is the Veda of the Fire Priest, consisting of occult formulas and spells. This Book of Spells, the last of the Vedas, is completely different from the other three Vedas and is next in importance to Rig Veda with regard to history and sociology.
A different spirit pervades this Veda. Its hymns are of a more diverse character than the Rig Veda and are simpler in language. In fact, many scholars do not consider it part of the Vedas at all. This Veda consists of spells and charms prevalent at the time it was written, and it portrays a clearer picture of the Vedic society.