It seems to me that all the effort to distinguish between pure land rent that should qualify for taxation and non-pure land rent that should be tax-exempt misses a crucial point. The search for such "unearned" rent or "income" is envy or covetousness in the guise of promoting the efficient use of resources. Marx and Marxists are more upfront about it when they declare their war on private property and seek to expropriate landowners of their entitlement to them. All land is to be held or owned by someone. I don't see what rightful business it is of anyone else to insist that some plot of land be put to this or that use, other than what the current owner or title holder chooses to do with it. The fact that an appreciation in the value of undeveloped land (received by the seller) is not added to GDP is beside the point. It is not added because it is properly considered to be a transfer payment. The new purchaser(s) must have earned income (from current production), which already would be included in the estimated GDP. Had the owner of the land hired people to work on it -- that is improved upon its "usefulness" -- that expenditure would have been added to GDP as well. If the people hired had been taken away from doing something else in the economy, the estimated GDP may not then be different from the previous one in which income earned in some other activity was used or added to some other borrowed funds to purchase the undeveloped land. I think it is a lucky thing for economic well-being of humanity that Henry George's single tax proposal has not been adopted across the world. Pat Gunning has avoided responding to the request to name a proper tax, other than the land rent tax. His focus on the entrepreneurial activity of a landowner or purchaser can hardly be a satisfactory answer to that request. I think everyone who earns income from whatever source has to pay a tax, perhaps a flat 10%. This because everyone enjoys the public goods provided by government, including national defense, the police service, and the administration of justice. The attempt to gang up on landowners should be seen for what it is: free-ridership in the enjoyment of public goods clothed in the guise of the pursuit of economic efficiency. James Ahiakpor