Sir, it is notorious that the slave traders of this District advertise for slaves in the newspapers of the neighboring counties of Maryland, to be delivered in any numbers at their slave pens in this city; and that they have agents, in the city and out of it, who are engaged in supplying victims for their shambles. Since the gentleman from Indiana was elected to this Congress, and, I believe, since he took his seat in this Congress, one coffle of about sixty slaves came, chained and driven, into this city; and at about the same time another coffle of a hundred. Here they were lodged for a short period, were then sold, and went on their returnless way to the ingulfing south. Sir, all this is done here under our own eyes, and within hearing of our own ears. All this is done now, and it has been done for fifty years,--ever since the seat of the national government was established in this place, and ever since Congress, in accordance with the constitution, has exercised “_exclusive_ legislation” over it. But the gentleman from Indiana, though accustomed to visit this District from his boyhood, has “never seen a negro sold here;”--he has “never seen a band of negroes taken off by the slave trader;” he does not remember “to have seen the slave trader himself;” he knows “nothing of the ‘slave pen’ that is so much talked about.” Sir, the eye sees, not less from the inner than from the outer light. The eye sees what the mind is disposed to recognize. The image upon the retina is nothing, if there be not an inward sense to discern it. The artist sees beauty; the philosopher sees relations of cause and effect; the benevolent man catches the slightest tone of sorrow; but the insensate heart can wade through tears and see no weeping, and can live amidst groans of anguish, and the air will be a non-conductor of the sound. I know a true anecdote of an American gentleman who walked through the streets of London with a British nobleman; and being beset at every step of the way by squalid mendicants, the American, at the end of the excursion, adverted to their having run a gantlet between beggars. “What beggars?” said his lordship; “_I have seen none_.”