Hindu texts "Śruti" refers to the body of most authoritative, ancient religious texts, believed to be eternal knowledge authored neither by human nor divine agent but transmitted by sages ("rishis"). These comprise the central canon of Hinduism. It includes the four Vedas including its four types of embedded texts - the Samhitas, the Brahmanas, the Aranyakas and the early Upanishads. Of the "Shrutis" (Vedic corpus), the Upanishads alone are widely influential among Hindus, considered scriptures par excellence of Hinduism, and their central ideas have continued to influence its thoughts and traditions. The "Smriti" texts are a specific body of Hindu texts attributed
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