Roger North’s The Musicall Grammarian 1728 is a treatise on musical eloquence in all its branches. Of its five parts, I and II, on the orthoepy, orthography and syntax of music, constitute a grammar; III and IV, on the arts of invention and communication, form a rhetoric; and V, on etymology, consists of a history. Two substantial chapters of commentary introduce the text, which is edited here for the first time in its entirety: Jamie Kassler places his treatise within the broader context not only of North’s musical and non-musical writings but also their relation to the intellectual ferment of the seventeenth and eighteenth centuries and Mary Chan describes physical and textual aspects of the treatise as evidence for North’s processes of thinking about musical thinking.