Linguistics is the scientific study of language, involving analysis of language form, language meaning, and language in context. Language use was first systematically documented in Mesopotamia with extant lexical lists of the 3rd to the 2nd Millennia BCE, offering glossaries on Sumerian cuneiform usage and meaning, and phonetical vocabularies of foreign languages. Later, Sanskrit would be systematically analyzed, and its rules described by Pāṇini in the Indus Valley. Aristotle laid the foundation of Western linguistics as part of the study of rhetoric in his Poetics ca. 335 BC. Traditions of Arabic grammar and Hebrew grammar developed during the Middle Ages in a religious context like Pānini's Sanskrit grammar.