Regarding Bruce Caldwell's query about the passage in Smith:

  "People of the same trade seldom meet together, even for merriment 
and diversion, but the conversation ends in a conspiracy against the 
public, or in some contrivance to raise prices. It is impossible 
indeed to prevent such meetings, by any law which either could be 
executed, or would be consistent with liberty and justice. But though 
the law cannot hinder people of the same trade from sometimes 
assembling together, it ought to do nothing to facilitate such 
assemblies; much less to render them necessary." Book 1, Ch. X, Part II. (WN).

Sumitra Shah