The problem of the twentieth century is the problem of the color-line,—the relation of the darker to the lighter races of men in Asia and Africa, in America and the islands of the sea. It was a phase of this problem that caused the Civil War; and however much they who marched South and North in 1861 may have fixed on the technical points of union and local autonomy as a shibboleth, all nevertheless knew, as we know, that the question of Negro slavery was the real cause of the conflict.
