The active propaganda for the modern single tax has been in progress for less than half a century, yet nearly every principle around which the theory is formulated was propounded years before, in various countries, by numerous writers. The exposition of the nature of rent by Ricardo and Mill gave strength to the ideas of social wealth and unearned increment. The principle of the natural right to land was developed by a number of early philosophical writers. Adam Smith has many references to the nature of rents, and indicates their peculiar ability to bear the burden of taxes. Other writers acquiesced, yet none went so far as to attempt to make any practical application of their teachings.

1 Carl C. Plehn, Introduction to Public Finance, third ed., p. 135.

Progress and Poverty. - The first attempt to put these teachings to practical use was made by Henry George, in the publication of his well-known work, Progress and Poverty, in 1879. Nor did he stop with the publication of the principles in which he so firmly believed, but devoted the rest of his life to securing their application to actual economic conditions. For a number of years before the publication of his work, George had lived in California, where he had a chance to witness in a few years developments in land ownership which ordinarily occur only after decades. The situation was caused by the phenomenal development which followed the discovery of gold. While most of the principles enunciated in Progress and Poverty are not new, George did not know that they had been stated previously, and they were formulated by him out of his own thinking and experiences. While much other literature has been written on the single tax, Progress and Poverty still holds first rank as exponent of the doctrine.