It was in the year 1869 that, impressed with the degree in which, even during the last twenty years, when the world seemed so wholly occupied with other matters, the socialist ideas of speculative thinkers had spread among the workers in every civilized country, Mr. Mill formed the design of writing a book on Socialism. Convinced that the inevitable tendencies of modern society must be to bring the questions involved in it always more and more to the front, he thought it of great practical consequence that they should be thoroughly and impartially considered, and the lines pointed out by which the best speculatively-tested theories might, without prolongation of suffering on the one hand, or unnecessary disturbance on the other, be applied to the existing order of things.