There are in this volume sentences written as long ago/ as 1957. What was then projected as the third part of a modest discussion of then current issues has, through some fifteen revisions, now expanded into its own three parts. Of the project as originally conceived, the first part, itself grown too large, was published (prematurely, I now believe) in 1965 (Stratification of Behaviour). The second part, which was to be on language proper, was abandoned around 1967; such materials on language as I need for the present work are now mostly compressed into Chapter 1, with some scatterings...