The article discusses Fyodor Buslaev’s viewpoint on the metalinguistic reflection in his fundamental ‘Historical Anthology of Church Slavonic and Old Russian’ (Moscow, 1861). The anthology can serve as an introduction to the study of the early Slavic-Russian grammatical tradition. Excerpts from philology-related works described and commented on by Buslaev vividly show what interested Slavic scribes and what helped to evolve their grammatical thinking between the late 9th century and the first third of the 18th century. It is argued that Buslaev played a vital role in the formation of today’s concept of how grammatical thought in Russia evolved. The paper discusses what Buslaev thought about the Bulgarian origin of the tales by Chernorizets Сhrabr and the role of spelling as a major trend in the development of grammatical knowledge up to the 1630–1640s. Of special interest is Buslaev’s idea that the second, Moscow, edition of grammar by Melety Smotritsky published in 1648 is not identical to the first edition published in 1619.