I had no idea that Herbert Spencer enjoyed such popularity in his own time. It's a tragedy that Spencer's thought was largely supplanted by Marxism and its spores.
"He was probably the first, and possibly the only, philosopher in history to sell over a million copies of his works during his own lifetime. In the United States, where pirated editions were still commonplace, his authorised publisher, Appleton, sold 368,755 copies between 1860 and 1903. This figure did not differ much from his sales in his native Britain, and once editions in the rest of the world are added in the figure of a million copies seems like a conservative estimate."
https://en.wikipedia.org/wiki/Herbert_Spencer#Political_views
"He was probably the first, and possibly the only, philosopher in history to sell over a million copies of his works during his own lifetime. In the United States, where pirated editions were still commonplace, his authorised publisher, Appleton, sold 368,755 copies between 1860 and 1903. This figure did not differ much from his sales in his native Britain, and once editions in the rest of the world are added in the figure of a million copies seems like a conservative estimate."
https://en.wikipedia.org/wiki/Herbert_Spencer#Political_views