Book excerpt: In any course of historical and comparative linguistics there will be students of different language backgrounds, different levels of linguistic training, and different theoretical orientation. This textbook attempts to mitigate the problems raised by this heterogeneity in a number of ways. Since it is impossible to treat the language or language family of special interest to every student, the focus of this book is on English in particular and Indo-European languages in general, with Finnish and its closely related languages for contrast. The tenets of different schools of linguistics, and the controversies among them, are treated eclectically and objectively; the examination of language itself plays the leading role in our efforts to ascertain the comparative value of competing theories. This revised edition (1989) of a standard work for comparative linguists offers an added introduction dealing mainly with a semiotic basis of change, a final chapter on aspects of explanation, particularly in historical and human disciplines, and added sections on comparative syntax and on the semiotic status of the comparative method.