Although I agree with Anthony Waterman concerning the importance of drawing a difference between HET as IA and HET as HEA--with the latter of definite importance to economists--I still don't regard Samuelson's Canonical Classical Model as a contribution to anything.  I'm a bit pressed for time right now and can't dig up my copy; however, as I recall, the most startling omission from Samuelson's reinterpretation was that of the productivity-enhancing effects of the division of labor.  I guess it messed up the math.
   
  Sam Bostaph