This revised edition has a new introduction dealing mainly with a semiotic basis of change and a final chapter on aspects of explanation, particularly in historical and human disciplines, has been added. Minor changes have been made in the bulk of the text. Chapter 11 now includes a section on comparative syntax and chapter 13 includes a brief addition on the semiotic status of the comparative method. The bibliography has been updated with a selection from the overwhelming amount of material which has appeared in the intervening years. The index has been adapted to include the new material.
