the same text. The texts were subsequently "proof-read" by comparing the different recited versions. Forms of recitation included the (literally "mesh recitation") in which every two adjacent words in the text were first recited in their original order, then repeated in the reverse order, and finally repeated in the original order. That these methods have been effective, is attested to by the preservation of the most ancient Indian religious text, the Rigveda, as redacted into a single text during the Brahmana period, without any variant readings within that school. The Vedas were orally transmitted by memorization, and were written down only after 500 BCE,</ref> All printed editions of the Vedas that survive in the modern times are likely the version existing in about the 16th century CE. Four Vedas The canonical division of the Vedas is fourfold () viz., Rigveda (RV) Yajurveda (YV, with the main division TS vs. VS) Samaveda (SV) Atharvaveda (AV) Of these, the first three were the principal original division, also called ""; that is, "the triple science" of reciting hymns (Rigveda), performing sacrifices (Yajurveda), and chanting songs (Samaveda). The Rig Veda most likely was composed between 1500 BCE and 1200 BCE. Witzel notes that it is the Vedic period itself, where incipient lists divide the Vedic texts into three (trayī) or four branches: Rig, Yajur, Sama and Atharva. Each Veda has been subclassified into four major text types – the Samhitas (mantras and benedictions), the Aranyakas (text on rituals, ceremonies such as newborn baby's rites of passage, coming of age, marriages, retirement and cremation, sacrifices and symbolic sacrifices), the Brahmanas (commentaries on rituals, ceremonies and sacrifices), and the Upanishads (text discussing meditation, philosophy and spiritual knowledge). The Upasanas (short ritual worship-related sections) are considered by some scholars as the fifth part. Witzel notes that the rituals, rites and ceremonies described in these ancient texts reconstruct to a large degree the Indo-European marriage rituals observed in a region spanning the Indian subcontinent, Persia and the European area, and some greater details are found in the Vedic era texts such as the Grhya Sūtras. Only one version of the Rigveda is known to have survived into the modern era. Several different versions of the Sama Veda and the Atharva Veda are known, and many different versions of the Yajur Veda have been found in different parts of South Asia. The texts of the Upanishads discuss ideas akin