this terrible baptism of blood and fire through which our nation is passing . . . not as has been most cruelly affirmed, because of the presence of men of color in the land, but by malignant . . . vices, nursed into power . . . at the poisoned breast of slavery, it will come at last . . . purified in its spirit freed from slavery, vastly greater . . . than it ever was before in all the elements of advancing civilization.