In the , language is observed in a manner that has no parallel among Greek or Latin grammarians. Pāṇini's grammar, according to Renou and Filliozat, defines the linguistic expression and a classic that set the standard for the Sanskrit language. Pāṇini made use of a technical metalanguage consisting of a syntax, morphology and lexicon. This metalanguage is organised according to a series of meta-rules, some of which are explicitly stated while others can be deduced. Despite differences in the analysis from that of modern linguistics, Pāṇini's work has been found valuable and the most advanced analysis of linguistics until the twentieth century.