I think, then, that the scientific idea of the ether, as a universal medium pervading all space, and permeating all substance, will help us to see that many things which are popularly called supernatural, are to be attributed to the action of known laws working under, as yet, unknown conditions, and therefore, when we are confronted with strange phenomena, a knowledge of the general principles involved, will show us in what direction to look for an explanation. Now applying this to the present subject, we may reasonably argue, that since all physical matter is scientifically proved to consist of the universal ether in various degrees of condensation, there may be other degrees of condensation, forming other modes of matter, which are beyond the scope of physical vision and of our laboratory apparatus. And similarly, we may argue, that just as various effects can be produced on the physical plane, by the action of etheric waves of various lengths, so other effects might be produced on these finer modes of matter, by etheric waves of other lengths. And in this connection we must not forget that a gap occurs between the "dark heat" groups and the Hertzian group, consisting of five octaves of waves, the lengths of which have been theoretically calculated, but whose action has not yet been discovered. Here we admittedly have a wide field for the working of known laws under as yet unknown conditions; and again, how can we say that there are not ranges of unknown waves, yet smaller than the minute ultra-violet ones, which commence the present known scale, or transcending those largest ones, which bear our messages across the Atlantic? Mathematically, there is no limit to the scale in either direction; and so, taking our stand on the demonstrated facts of science, we find, that the known laws of Nature point to their continuation in modes of matter and of force, of which we have as yet no conception. It is therefore not at all necessary to spurn the ground of established science to spread the wings of our fancy; rather it affords us the requisite basis from which to start, just as the aeronaut cannot rise without a solid surface from which to spring.