Sibawayhi, a non-Arab, was the first to write on Arabic grammar and the first to explain Arabic grammar from a non-Arab perspective. Both Sibawayhi and his teacher al-Farahidi made the earliest and most significant formal recording of the Arabic language. This book argues that the science of Arabic grammar owes its origins to a set of methods developed independently to form the Islamic legal system, not to Greek or other foreign influence. These methods and criteria were adapted to create a grammatical system brought to perfection by Sibawayhi in the late second/eighth century. It describes the evolution of the new science of grammar, and makes detailed comparisons between the technical terms of law and grammar to show how the vocabulary of the law was applied to the speech of the Arabs. It also sheds light on Sibawayhi's method in producing his magisterial Kitb. This is a corrected version, with considerable Addenda, of Michael G. Carter's 1968 Oxford doctoral thesis, Sibawayhi's Principles of Grammatical Analysis.