We are in the present day upon the trace of a great many important facts relating to the imponderable agencies employed in nature. Light, heat, and electricity are no longer the simple matters, or effects of matter, that they have aforetime seemed to be. New wonders point to more beyond. In magnetism, the researches of Faraday and others, are beginning to open in our own day, the Book of Nature, at a page of the very first importance to the naturalist; but the contents of which until this time have been wholly unsuspected. Behind a cloudy mass of fraud and folly, while the clouds shift, we perceive a few dim stars, to guide us toward the discovery of wondrous truths. There are such truths which will hereafter illustrate the connection, in many ways still mysterious, between the body of man and the surrounding world. Wonderful things have yet to be revealed, on subjects of a delicate and subtle texture. It behooves us in the present day, therefore, to learn how we may keep our tempers free from prejudice, and not discredit statements simply because they are new and strange, nor, on the other hand, accept them hastily without sufficient proof. On questionable points, which are decided by research and weight of evidence, it would be well if it were widely understood that it is by no means requisite for every man to form an Ay or Nay opinion. Let those who have no leisure for a fair inquiry play a neutral part. There are hundreds of subjects which we have never examined, nor ever could or can examine, upon which we are all, nevertheless, expressing every day stubborn opinions. We all have to acquire some measure of the philosophic mind, and be content to retain a large army of thoughts, equipped each thought with its crooked bayonet, a note of interrogation. In reasoning, also, when we do reason, we have to remember fairly that “not proven” does not always mean untrue. And in accepting matters on testimony, we must rigidly preserve in view the fact, that, except upon gross objects of sense, very few of us are qualified by training as observers. In drawing delicate conclusions from the complex and most dimly comprehended operations of the human frame observed in men and women, the sources of fallacy are very numerous. To detect and acknowledge these, to get rid of them experimentally, is very difficult, even to the most candid and enlightened mind.