Grammar speaks

 "I have four parts: letters, literature, the man of letters, and literary style. Letters are what I teach, literature is I who teach, the man of letters is the person whom I have taught, and literary style is the skill of a person whom I form. I claim to speak also about the nature and practice of poetry. Nature is that from which speech is formed. Practice occurs when we put that material into use. To these we add the matter, so as to know what we must talk about. Speech itself is taught in three steps; that is, from letters [i.e. phonemes, the basic units of sound in a particular language], syllables, and words."
~Grammar, explaining her profession and field of study in The Marriage of Philology and Mercury, by Martianus Capella (fl. A.D. 410-420)