One peculiarity of this age is the sudden acquisition of much physical knowledge. There is scarcely a department of science or art which is the same, or at all the same, as it was fifty years ago. A new world of inventions--of railways and of telegraphs--has grown up around us which we cannot help seeing; a new world of ideas is in the air and affects us, though we do not see it. A full estimate of these effects would require a great book, and I am sure I could not write it; but I think I may usefully, in a few papers, show how, upon one or two great points, the new ideas are modifying two old sciences--politics and political economy. Even upon these points my ideas must be incomplete, for the subject is novel; but, at any rate, I may suggest some conclusions, and so show what is requisite even if I do not supply it.
If we wanted to describe one of the most marked results, perhaps the most marked result, of late thought, we should say that by it