“Look at the magnitude of this subject! One sixth of our population, in round numbers — not quite one sixth, and yet more than a seventh, — about one sixth of the whole population of the United States are slaves! The owners of these slaves consider them property. The effect upon the minds of the owners is that of property, and nothing else — it induces them to insist upon all that will favorably affect its value as property, to demand laws and institutions and a public policy that shall increase and secure its value, and make it durable, lasting and universal. The effect on the minds of the owners is to persuade them that there is no wrong in it.”