Hindu texts Vedas: the Rigveda, the Yajurveda, the Samaveda and the Atharvaveda. Each Veda has been subclassified into four major text types – the Samhitas (mantras and benedictions), the Aranyakas (text on rituals, ceremonies, sacrifices and symbolic-sacrifices), the Brahmanas (commentaries on rituals, ceremonies and sacrifices), and the Upanishads (text discussing meditation, philosophy and spiritual knowledge). The Upanishads are a collection of Hindu texts which contain some of the central philosophical concepts of Hinduism. The Upanishads are commonly referred to as "Vedānta", variously interpreted to mean either the "last chapters, parts of the Veda" or "the object, the highest purpose of the Veda".
Vedas period, giving rise to various recensions of the text. Some texts were revised into the modern era, raising significant debate on parts of the text which are believed to have been corrupted at a later date. The Vedas each have an Index or Anukramani, the principal work of this kind being the general Index or "". Prodigious energy was expended by ancient Indian culture in ensuring that these texts were transmitted from generation to generation with inordinate fidelity. For example, memorization of the sacred "Vedas" included up to eleven forms of recitation of the same text. The texts were subsequently