It has been affirmed that the progress of physical science has destroyed in this nineteenth century all belief in the actual occurrence of the supernatural, and that it now prevails only in some of the dark corners of Christendom. The widespread belief in the phenomena of spiritualism, which is certainly very far from being confined to religious men, and from which some students of physical science have not been exempt, is a striking proof of the contrary. All that can be affirmed with truth is that, in these modern times, these forms of belief have taken a new direction. Modern science has done much to establish and spread the belief that the operations of all natural, _i.e._ material forces are uniform. Many of its students have even brought themselves to the belief that the occurrence of any event whose existence is due to the action of any other than the known forces of nature, is impossible: though this is far from being the invariable, and is certainly not the necessary result of its study. Still, probably, the most ardent votary of these opinions would find it difficult to keep himself wholly free from terrors arising from unseen causes, if they were aroused by a suitable apparatus. The study of physical science is far from being a universal safeguard against the invasions of superstition. Its causes lie far more deeply rooted in our nature than the principles of physical science can reach. Nor is it able to guard against an extravagant use of the imagination. Whether, in the present state of our philosophy, we have fully penetrated to the depths of this principle thus working in the mind of man, may admit of doubt; but its presence there, as an essential portion of our nature, is an unquestionable fact. We are not without the means of getting a general idea of its character. It is doubtless intimately connected with those principles of our nature which constitute man a religious being, and which form a fundamental part of his mental constitution. As such it must, like all our other faculties, have a legitimate and an illegitimate action. It points, as we shall see, to the existence of the supernatural. A rational religion forms the object for its appropriate exercise. Whenever man has been destitute of this, and his reason has been weak, this principle, devoid of its proper object, has always manifested itself in various forms of extravagance. So powerful is it in the human mind that even avowed atheism has not been proof against its power. Julius Cæsar was an atheist, and possessed one of the most powerful minds that ever inhabited the human frame. Yet, on the great day of his triumph, he ascended the steps of the Capitol for the purpose of averting an avenging Nemesis. Napoleon the First was no atheist, though few persons who have ever lived have been more free from the restraints of religion or superstition. Although he possessed a mighty intellect and was no stranger