Any good doctor will know what a healthy body is like, though he may spend much time treating the diseases that inflict it. In similar fashion, a good economist should know what a healthy economy is like before the insertions of "monopoly, monopsony, oligarchy, collusion, regulation, corruption and frictional elements". The political economy of the 18th and 19th centuries stressed the way people behaved without these insertions. Once the basics were solidified, the insertions could be dealt with - if necessary, one by one. However, modern economics tries to deal with the mixture of "insertions" - an impossible feat that is quite beyond the capabilities of modern neo-classicals. Which doesn't stop them from trying. Harry Pollard