A sutra is a literary rule or aphorism, or a collection of them. The word "sutra" comes from the Sanskrit word "sūtra," which means "string" or "thread". Sutras are a genre of ancient and medieval Indian texts found in Hinduism, Buddhism, and Jainism. In Hinduism, sutras are a distinct type of literary composition, a compilation of short aphoristic statements. Each sutra is any short rule, like a theorem distilled into few words or syllables, around which teachings of ritual, philosophy, grammar, or any field of knowledge can be woven. The oldest sutras of Hinduism are found in the Brahmana and Aranyaka layers of the Vedas. In Buddhism, sutras, also known as suttas, are canonical scriptures, many of which are regarded as records of the oral teachings of Gautama Buddha. Similarly, in Jainism, sutras, also known as suyas, are canonical sermons of Mahavira contained in the Jain Agamas as well as some later (post-canonical) normative texts. The actual teaching instruction in sutras usually follows a simple, easy-to-understand form that is rich in parables and allegories.