Organizing strictly all the matter of my book along these two lines of Personality and Reciprocity, notwithstanding much in it that was crude and more that was redundant and something that was ill-reasoned and unsound, the book made on account of this original mode of treatment an immediate impression upon the public, particularly upon teachers and pupils; new streaks of light could not but be cast from these new points of view, upon such topics especially as Land and Money and Foreign Trade; and nothing is likely ever to rob the author of the satisfaction, which he is willing to share with the public, of having contributed something of importance both in substance and in feature to the permanent up-building of that Science, which comes closer, it may be, to the homes and happiness and progress of the People, than any other science. And let it be said in passing, that there is one consideration well-fitted to stimulate and to reward each patient and competent scientific inquirer, no matter what that science may be in which he labors, namely, this: Any just generalization, made and fortified inductively, is put thereby beyond hazard of essential change for all time; for this best of reasons, that God has constructed the World and Men on everlasting lines of Order. As successive editions of this first book were called for, and as its many defects were brought out into the light through teaching my own classes from it year after year, occasion was taken to revise it and amend it and in large parts to rewrite it again and again; until, in 1883, and for the eighteenth edition, it was recast from bottom up for wholly new plates, and a riper title was ventured upon,--"Political Economy,"--instead of the original more tentative "Elements." Since then have been weeded out the slight typographical and other minute errors, and the book stands now in its ultimate shape.