Henry George's _Progress and Poverty_ seems a valuable contribution to economics; an overlooked jewel.
It contains the intriguing discernment that perhaps capital and labor are united in their susceptibility to the landed, and share a common interest, instead of being set against each other. In support of this, George points out that when wages drop or unemployment grows, interest rates typically plunge as well, an interesting observation.
I quibble a bit with the postulated benefits of increased population on the quality of life, which seems to conflate the effects of better technology with simple increases in population at one point. This part of his two-pronged poke at Malthusianism seems off.
The book clearly and preciently explains a powerful analysis of industrial society, with an elegant remedy. Both mindful of the wisdom of markets and the unfairness of typical industrial cities, George first details the analysis, then passionately advocates for his thoughtful 'cure'.
Overall, a very important and well-written book.
Progress and Poverty: An Inquiry Into the Cause of Industrial Depression and of Increase of Want with Increase of Wealth; the Solution (Fiftieth Anniversary Edition) (Hardcover)