Some time ago I delivered a lecture in the London Hall of Science on "Christianity and Slavery." Among my critics there was one gentleman, and the circumstance was so noteworthy that my friend the chairman expressed a wish, which I cordially echoed, that we might have the pleasure of hearing him again. A few days ago a pamphlet reached me on the subject of that lecture, written by my friendly opponent, who turns out to be the head of the Oxford House in Bethnal Green. Mr. Henson sends me the pamphlet himself "with his compliments," and I have read it carefully. Indeed, I have marked it in dozens of places where his statements strike me as inaccurate and his arguments as fallacious; and, on the whole, I think it best to give him a set answer in this journal. Mr. Henson's paper is not, in my opinion, a very forcible one on the intellectual side. But perhaps that is, in a certain sense, one of its merits; for the Christian case in this dispute is so bad that sentiment does it more service than logic. I must, however, allow that Mr. Henson is a courteous disputant, and I hope I shall reciprocate his good feeling. When he opposed me at the Hall of Science, he admits that I treated him "with a courtesy which relieves controversy of its worst aspects." I trust he will be equally satisfied with my rejoinder. Whenever I may have occasion to express myself strongly, I shall simply be in earnest about the theme, without the least intention of being discourteous. I mean no offence, and I hope I shall give none. Mr. Henson says he is dealing in a brief compass with a big subject, but "the outlines are clear, and may be perceived very readily by any honest man of moderate intelligence." Well, whether it is that I am not an honest man, or that I possess immoderate intelligence, I certainly do not see the outlines of the subject as Mr. Henson sees them. The relation of Christianity to slavery is an historical question, and Mr. Henson treats it as though it were one of dialectics. However, I suppose I had better follow him, and show that he is wrong even on his own ground. Mr. Henson undertakes to prove three things. (1) That slavery is flatly opposed to the teaching of the New Testament. (2) That the abolition of slavery in Europe was mainly owing to Christianity. (3) That at this present time Christianity is steadily working against slavery all over the world.