This article is an essay by a modern linguist in one aspect of the history of grammar. Grammar was a compulsory subject in the curriculum of the mediaeval university, and the golden age of scholasticism produced a number of interesting theories of grammar; this article is concerned with the theory of one group in particular, i.e. the Modistae, speculative grammarians who were active in the thirteenth and fourteenth centuries. The Modistae wrote their treatises in Latin and drew upon Latin to illustrate their theories. In addition they made of Latin an idealized language, a kind of “second-order-” or metalanguage, and it was from the standpoint of this idealized language that all grammatical speculation and pedagogy were to be carried out. This is an attitude which has persisted up to the present day and one which has considerably influenced the teaching of grammar and foreign languages since the Middle Ages.