I'm reading through some of my grandparents' files of correspondence; they were great correspondents, and kept carbons of their outgoing letters and originals of what they received. This is an excerpt from a 1957 letter from the executive secretary of a foundation which sponsored my grandfather's work, Vie Peterson (also a wonderful correspondent!) and was written in response to a draft of a document he was assembling as an introduction to Henry George. (A much later version of that paper is available here.)
"Should we elaborate why George insisted on one tax? He felt that the economic rent of land was the true national income. He felt any tax on production was a form of penalty on man's industry and thrift. He felt that every step forward that man makes in raising himself and in improving civilization as a whole would be reflected in land values and provide an increasing source of revenue which he believed would be sufficient for the national needs. As a family lives on a set income, George believed that a nation should do likewise. It would be necessary, it seems to me, to indicate that at the present time with the national debt so high and with other complications a tax on land values alone might not be sufficient, but the purpose of this statement is to show what George had in mind in his day which was not burdened with debt as is our own?
In another, slightly earlier, letter, Vie writes,
"... George believed that easy access to land would overcome unemployent, would eliminate reliance on government aid, and therefore simplify government structure, etc. "