|Grammar (left) and Priscian meet|
Grammar had its fans in the Classical and early Medieval eras, however, and none more zealous than Priscianus Caesariensis. We don't know too many details about Priscian, but we know he flourished around 500 CE, because that's about when his famous work on grammar appears.
According to Cassiodorus (c.485-c.585), who was writing during the administration of Theodoric of the Ostrogoths, Priscian was born in Caesarea, in what is now Algeria. Cassiodorus himself lived for a while in Constantinople, and he tells us that Priscian taught Latin in Constantinople for a time.
Priscian wrote a work called De nomine, pronomine et verbo (On noun, pronoun and verb), probably as an instructional tool for his Greek-speaking students. He also translated some Greek rhetorical exercises into Latin in Praeexercitamina (rhetorical exercises). There were also some minor works that don't concern us, because we need to talk about his 18-volume masterpiece, Institutiones grammaticae (Foundations of grammar). He patterned it works of Greek grammar by Apollonius Dyscolus and the Latin grammar of Flavius Caper. His numerous examples from Latin literature mean we have fragments of literature that would otherwise have been lost to us.
Priscian became popular: his work was quoted for the next few centuries, and copies became numerous enough—and his scholarship good enough—that this work became the standard grammar text for 1000 years after his time. We know a copy made it to England by 700; it was quoted by Bede and Aldhelm and copied by Hrabanus Maurus. It was a standard text centuries later at Oxford and Cambridge.
Manuscripts (there are about 1000 copies extant) exist from as early as the 9th century, and in 1470 it was still important enough that it was printed in Venice.