Although in our present ordinary state of existence we are permitted to see only "as through a glass darkly," ignorant of many of the powers and processes of nature, as well as of the causes to which they are to be ascribed, we are not, therefore, entitled to set limits to her operations, and to say to her, "Hitherto shalt thou go, and no further! "We must not presume, says Glanvill, to assign bounds to the exercise of the power of the Almighty, nor are these operations and that power to be controlled by the arbitrary theories and capricious fancies of man. We are surrounded by the incredible--the seemingly miraculous. Who would not ask for demonstration when told that a gnat's wing, in its ordinary flight, beats many hundred times in a second? But what is this, when compared to the astonishing truths which modern optical inquiries reveal--such as teach us that the sensation of violet light affects our eyes 707 millions of millions of times per second in order to effect that sensation? How strangely must they estimate nature, how highly must they value their own conceits, who deny the possibility of any cause of any effect, merely because it is incomprehensible. In fact, what do men comprehend? What do they know of causes? When Newton said that gravitation held the world together, he assigned no reason why the heavenly bodies do not fly off from each other into infinite space. The discoverer of etheric force is able to give the reasons for, and the explanations of, the laws involved in all that he asserts; or, rather, all that he propounds; for, with the true humility of wisdom, he asserts nothing. Newton at first thought that he had discovered in electricity the ether which he asserted pervades all nature, until, by repeated experiments, he became convinced of the insufficiency of that principle to explain the phenomena. Other philosophers have speculated upon magnetism in the same way, and upon the similarity between magnetism and electricity. Mr. Keely's experiments show that the two are, in part, antagonistic, and that both are but modifications of the one force in nature. There have been some physiologists who have maintained that the nerves are merely the conductors of some fluid from the brain and spinal cord to the different parts of the body, and that this circulating fluid is capable of an external expansion, which takes place with such energy as to form an atmosphere, or sphere of activity, similar to that of electrical bodies. Dr. Roget observes that the velocity with which the nerves subservient to sensation transmit the impressions they receive at one extremity, along their whole course, exceeds all measurement, and can be compared only to that of electricity passing along a conducting wire. A comparison with gravity would have been nearer the truth, though no computation ever has been made, or ever can be made, between the flight of gravity and of electricity, so infinitely swifter is the former.