From the days of the Roman Empire, the study of grammar was, and never ceased to be, the basis of the conscious and rational knowledge of the Latin tongue. The Roman boys studied it at Rome; the Latin-speaking provincials studied it, and all people of education who remained in the lands of western Europe which once had formed part of the Empire; its study was renewed under Charlemagne; he and Alcuin and all the scholars of the ninth century were deeply interested in what to them represented tangible Latinity, and in fact was to be a chief means by which their mediaeval civilization should maintain its continuity with its source. For grammar was most instrumental in preserving mediaeval Latin from violent deflections, which would have left the ancient literature as the literature of a forgotten tongue. Had mediaeval Latin failed to keep itself veritable Latin; had it instead suffered transmutation into local Romance dialects, the Latin classics, and all that hung from them, might have become as unknown to the Middle Ages as the Greek, and even have been lost forever. It was the study of Latin grammar, with classic texts to illustrate its rules, that kept Latin Latin, and preserved standards of universal usage throughout western Europe, by which one language was read and spoken everywhere by educated people. From century to century this language suffered modification, and varied according to the knowledge and training of those who used it; yet its changes were never such as to destroy its identity as a language, or prevent the Latin writer of one age or country from understanding whatever in any land or century had been written in that perennial tongue.