The relations of our sense-organs to the various degrees of matter, to solids, fluids, gases, atmosphere and ether, vary in different individuals to such a wide extent as to create the greatest diversity of normal faculty. The average wool-sorter will outvie an artist in his perception of colour shades. An odour that is distinctly recognizable by one person will not be perceptible to others. In the matter of sound also the same differences of perception will be noted. On a very still night one can hear the sugar canes growing. Most people find the cry of a bat to be beyond their range. The eye cannot discern intervals of less than one-fiftieth of a second. Atmospheric vibration does not become sound until a considerable frequency is attained. Every movement we make displaces air but our sense of touch does not inform us of it, but if we stand in a sunbeam the dust particles will show that it is so. Our sense of feeling will not register above certain degrees of heat or below certain degrees of cold. Sensation, moreover, is not indefinitely sustained, as anyone may learn who will follow the ticking of a watch for five minutes continuously. But quite apart from the sense and range of our perceptions, the equality of a sense-impression is found to vary with different persons, affecting them each in a different way. We find that people have "tastes" in regard to form, colour, flavour, scent, sound, fabric and texture. The experience is too general to need illustration, but we may gather thence that, in relation to the nervous system of man, every material body and state of matter has a variable effect. These remarks will clear the ground for a statement of my views upon the probable effect a crystal may have upon a sensitive person. CHAPTER II. MATERIALS AND CONDITIONS The crystal is a clear pellucid piece of quartz or beryl, sometimes oval in shape but more generally spherical. It is accredited by Reichenbach and other researchers with highly magnetic qualities, capable of producing in a suitable subject a state analogous to the ordinary "waking trance" of the hypnotists. It is believed that all bodies convey, or are the vehicles of certain universal property called od or odyle (od-hyle), which is not regarded as a force but as an inert and passive substance underlying the more active forces familiar to us in kinetic, calorific and electrical phenomena. In this respect it holds a position analogous to the argon of the atmosphere, and is capable of taking up the vibrations of those bodies to which it is related and which it invests. It would perhaps not be amiss to regard it as static ether. Of itself it has no active properties, but in its still, well-like depths, it holds the potentiality of all magnetic forces.