The four Vedas
The term Veda (“science” or “knowledge”) refers to the orthodox, revealed sacred scripture of India as a whole, which is divided into four individual scriptures: the Rig Veda, Yajur Veda, Sama Veda, and Atharva Veda, each of which is quite ancient. They are sometimes also called Samhitas (“collections”) because they are gatherings of various hymns, prayers, and spiritual lore. The oldest, the Rig Veda, is said to date back to at least 1500 BCE. Each Veda has attached to it a set of more recent scriptures, known as Brahmanas, Aranyikas, and Upanishads. The Vedas are conventionally believed by Western scholars to have been composed and passed on orally between 1500-600 BCE, and put into writing sometime after 1000 BCE. Yet most scholars acknowledge that the origins of the beliefs expressed in the Vedas are shrouded in mystery. Some Indian historians date certain hymns as far back as 4000 BCE or earlier.
The lengthy Vedas were each the responsibility of various brahman families, who collected and passed them down among themselves. Based on many internal references to sections of the Vedas and Upanishads that no longer exist, scholars have deduced that large amounts of the original scriptures have been lost.
The four castes
Also known as varna (“color”), caste traditionally divides Hindus into four major classes of society (with hundreds of sub-castes in between).
Below these are the outcastes, the so-called “untouchables,” who were considered to be outside the caste system and were required to perform the most menial tasks in Indian society. Mahatma Gandhi tried to change the way Indians perceive outcastes by calling them harijan, or “children of God.” It is essential to understand that these are societal rather than religious distinctions, and were imposed by the invading Aryans on an indigenous population that was darker-skinned. Each caste carries with it a specific svadharma, or set of responsibilities.