His concluding argument, and perhaps one of his strongest, is that founded upon the dignity of man, as conferring a pre-eminence upon the planet which has produced him. 'If,' he says, 'man be not merely capable of Virtue and Duty, of universal Love and Self-Devotion, but be also immortal; if his being be of infinite duration, his soul created never to die; then, indeed, we may well say that one soul outweighs the whole unintelligent creation.' And then, addressing the religious world, he urges that, if, as they believe, God _has_ redeemed man by the sacrifice of His Son, and _has_ given to him a revelation of His will, then indeed no other conception is possible than that he is the sole and highest product of the universe. 'The elevation of millions of intellectual, moral, religious, spiritual creatures, to a destiny so prepared, consummated, and developed, is no unworthy occupation of all the capacities of space, time, and matter.' Then with a chapter on 'The Unity of the World,' and one on 'The Future,' neither of which contains anything which adds to the force of his argument, the book ends. The publication of this able if rather vague and diffuse work, contesting popular opinions, was followed by a burst of indignant criticism on the part of a man of considerable eminence in some branches of physics--Sir David Brewster, but who was very inferior, both in general knowledge of science and in literary skill, to the writer whose views he opposed. The purport of the book in which he set forth his objections is indicated by its title--_More Worlds than One, the Creed of the Philosopher and the Hope of the Christian_. Though written with much force and conviction it appeals mainly to religious prejudices, and assumes throughout that every planet and star is a special creation, and that the peculiarities of each were designed for some special purpose. 'If,' he says, 'the moon had been destined to be merely a lamp to our earth, there was no occasion to variegate its surface with lofty mountains and extinct volcanoes, and cover it with large patches of matter that reflect different quantities of light and give its surface the appearance of continents and seas. It would have been a better lamp had it been a smooth piece of lime or of chalk.' It is, therefore, he thinks, prepared for inhabitants; and then he argues that all the other satellites are also inhabited. Again he says that 'when it was found that Venus was about the same size as the Earth, with mountains and valleys, days and nights, and years analogous to our own, the _absurdity_ of believing that she had no inhabitants, when no other rational purpose could be assigned for her creation, became an argument of a certain amount that she was, like the Earth, the seat of animal and vegetable life.' Then, when it was found that Jupiter was so gigantic 'as to require four moons to give him light, the argument from analogy that _he_ was inhabited became