But what does this term "grammar" exactly denote? On the plinths of the right bay of the great west doors of Chartres Cathedral are to be found statues of the Seven Liberal Arts. With reference to these statues, Dr. Clerval in his work on "Chartres, sa Cathedrale et ses Monuments," writes:-- "Les autres cordons representent les sept Arts liberaux qui ornaient l'esprit de la Vierge symbolises chacun par une femme portant les attributs de chaque science, et par un homme, le corypliee de cette science, assis devant un pupitre, avec plume, canif, encre, eponges, regles. Ainsi au bas du premier cordon de droite, c'est la Musique frappant trois cloches avec un marteau, et dessous Pythagore. Au second cordon a gauche en bas, c'est la Dialectique, portant un lizard subtil et un sceptre, et dessous Aristotle; puis la Rhetorique, discourant, et dessous Ciceron; la Geometrie avec un compas, et dessous Euclide; l'Arithmetique (en redescendant) avec un livre, et dessous Boece ou Pythagore; l'Astronomie regardant le Ciel et portant un boisseau, et dessous Plotonee, portant une lunette; enfin la Grammaire, assise, menacant de verges deux jeunes ecoliers lisant a ses pieds, et au-dessous Priscien ou Donat. Ces representations des Arts tres curieuses sont les plus anciennes avec celles de Laon. Elles s'expliquent a Chartres par les ecolatres de cette Eglise, specialement Thiery, auteur de l'Heptabuclion, vers 1140."[170] This passage may assist us in determining the meaning assigned to Grammar as one of the Seven Liberal Arts. It suggests that everything which was not music, eloquence, logic, mathematics, astronomy, geometry, was grammar, _i.e._ nearly the whole of the humanities; or, in other words, the study of grammar was synonymous with the study of "letters" so far as the term was then understood. In actual practice, however, grammar did not possess this connotation. This was due to the fact that a study of letters was not possible until a mastery of Latin had been acquired, and consequently it resulted that the term "grammar school" was applied to denote a place in which instruction was given in "Donat" or "Priscian." Donat was a Roman rhetorician who wrote _Ars Grammatica_ about the middle of the fourth century. His grammar was the most generally used elementary text-book on the subject. In its abbreviated form, which was the one in common use, it only consisted of eight or nine pages. Priscian was a grammarian who flourished in the early part of the sixth century, and who published, about 526, his _Institutiones Grammaticae_, a most elaborate and systematic treatise on Latin grammar. For over a thousand years Priscian's work was regarded as the leading and authoritative text-book on the subject.