The hypothesis of this book is that Indo-European was originally an isolating language that only gradually developed the complicated system of noun inflection presented in attested sources. In Shield"s view the earliest noun endings served as exponents of ergative and absolutive cases, with nouns being divided into three semantic categories, namely; inanimate, animate and natural agent.Like W.R. Schmalstieg, Shields combines sociolinguistic, phonlogical, and analogical approaches to language change, rejecting what both consider an over-emphasis on typology. In essence, this volume is a direct development of Schmalstieg"s call for "a new way of looking at many of the problems of Indo-European grammar" -set forth in his Indo-European Lingusitics: A New Synthesis. The purpose of this book is frankly heuristic: to stimulate further research and analysis.