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 Brahmanas (commentaries on rituals, ceremonies and sacrifices), and the Upanishads (texts discussing meditation, philosophy and spiritual knowledge). Some scholars add a fifth category – the Upasanas (worship). The various Indian philosophies and denominations have taken differing positions on the Vedas. Schools of Indian philosophy which cite the Vedas as their scriptural authority are classified as "orthodox" (āstika). Other śramaṇa traditions, such as Lokayata, Carvaka, Ajivika, Buddhism and Jainism, which did not regard the Vedas as authorities, are referred to as "heterodox" or "non-orthodox" (nāstika) schools. Despite their differences, just like the texts of the śramaṇa traditions, the layers of texts