I'd like to second the addition of Henry George, and supply some 
additional quotations, mostly quite brief:

"For as labor cannot produce without the use of land, the denial of 
the equal right to the use of land is necessarily the denial of the 
labor to its own produce."
Progress and Poverty (bk. VII, ch. I)

"So long as all the increased wealth which modern progress brings, 
goes but to build up great fortunes, to increase luxury, and make 
sharper the contest between the House of Have and the House of Want, 
progress is not real and cannot be permanent."
Progress and Poverty, Intrroduction

"What protectionism teaches us, is to do to ourselves in time of 
peace what enemies seek to do to us in time of war."
(No source, unfortunately)

Don Coffin