a Vyakhya is a comment by the reviewer. History Sutras first appear in the Brahmana and Aranyaka layer of Vedic literature. They grow in number in the Vedangas, such as the Shrauta Sutras and Kalpa Sutras. These were designed so that they can be easily communicated from a teacher to student, memorized by the recipient for discussion or self-study or as reference. A sutra by itself is condensed shorthand, and the threads of syllable are difficult to decipher or understand without associated scholarly Bhasya or deciphering commentary that fills in the "weft". The oldest manuscripts that have survived into the modern era that contain extensive sutras are part of the Vedas, dated from the late 2nd millennium BCE through to the mid 1st millennium BCE. The Aitareya Aranyaka, for example, states Winternitz, is primarily a collection of sutras. Their use and ancient roots are attested by sutras being mentioned in larger genre of ancient non-Vedic Hindu literature called Gatha, Narashansi, Itihasa, and Akhyana (songs, legends, epics, and stories). In the history of Indian literature, large compilations of sutras, in diverse fields of knowledge, have been traced to the period from 600 BCE to 200 BCE (mostly after Buddha and Mahavira), and this has been called the "sutras period". This period followed the more ancient Chhandas period, Mantra period and Brahmana period. Hinduism Some of the earliest surviving specimens of sutras of Hinduism are found in the Anupada Sutras and Nidana Sutras. The former distills the epistemic debate whether Sruti or Smriti or neither must be considered the more reliable source of knowledge, while the latter distills the rules of musical meters for Samaveda chants and songs. A larger collection of ancient sutra literature in Hinduism corresponds to the six Vedangas, or six limbs of the Vedas. These are six subjects that said in the Vedas to be necessary for complete mastery of the Vedas. The six subjects with their own sutras were "pronunciation (Shiksha), meter (Chandas), grammar (Vyakarana), explanation of words (Nirukta), time keeping through astronomy (Jyotisha), and ceremonial rituals (Kalpa). The first two, states Max Muller, were considered in the Vedic era to be necessary for reading the Veda, the second two for understanding it, and the last two for deploying the Vedic knowledge at yajnas (fire rituals). The sutras corresponding to these are embedded inside the Brahmana and Aranyaka layers of the Vedas. Taittiriya Aranyaka, for example in