My research examines linguistic awareness in the Greek world by focusing on ancient linguistic approaches which still inform the Modern Greek debate on the definition of a national language. The way that people represent language and communication processes is important to understand how social groups value and orient to language. While attention has already been given to the relationship between language and identity in the Ancient and Modern Greek worlds, little work has been done on these metalinguistic perspectives and little attention has been paid to the convergence between these perspectives in ancient and modern times. My research will fill this gap by proposing a comparative study between ancient linguistic sources and a modern theory called Aeolodoric theory, with the aim of better understanding ancient linguistic conceptions from a diachronic perspective, of providing a historical contextualisation of modern tendencies, and of evaluating the impact that linguistic conceptions have on the transmission of the Greek language. This research also engages with broad sociolinguistic issues, such as the role of artificial languages, their use to define collective identities, and the way in which linguistic varieties are related to each other in diglossic communities.