Sextus Empiricus is one of the most important ancient philosophical writers after Plato and Aristotle. His writings are our main source for the doctrines and methods of Scepticism. He probably lived in the second century AD. Eleven books of his writings have survived, covering logic, physics, ethics, and many other fields. Against the Grammarians is the first book of Sextus' Adversus Mathematicos, his broad-ranging polemic against the various liberal studies of classical learning. It is prefaced by a short general attack on the arts (included in this volume); then Sextus focuses on the grammatical writers of the classical era, categorizing, analysing, and criticizing their doctrines. The result is not only an invaluable source for ancient ideas about grammar, language, and literary technique, but an excellent example of sustained Sceptical reasoning. David Blank presents a new translation into clear modern English of this important treatise, together with the first ever commentary on the work. In an extended introduction he discusses Against the Grammarians in the broad context of Sextus' work as a whole, Scepticism in general, and the history of ancient writings in this field.