Our simile, indeed--be it once for all noted--is a most imperfect one. The range of human faculty cannot be truly expressed in any linear form. Even a three-dimensional scheme,--a radiation of faculties from a centre of life,--would ill render its complexity. Yet something of clearness will be gained by even this rudimentary mental picture;--representing conscious human faculty as a linear spectrum whose red rays begin where voluntary muscular control and organic sensation begin, and whose violet rays fade away at the point at which man's highest strain of thought or imagination merges into reverie or ecstasy. At both ends of this spectrum I believe that our evidence indicates a momentous prolongation. Beyond the _red_ end, of course, we already know that vital faculty of some kind must needs extend. We know that organic processes are constantly taking place within us which are not subject to our control, but which make the very foundation of our physical being. We know that the habitual limits of our voluntary action can be far extended under the influence of strong excitement. It need not surprise us to find that appropriate artifices--hypnotism or self-suggestion--can carry the power of our will over our organism to a yet further point. The faculties that lie beyond the _violet_ end of our psychological spectrum will need more delicate exhibition and will command a less ready belief. The actinic energy which lies beyond the violet end of the solar spectrum is less obviously influential in our material world than is the dark heat which lies beyond the red end. Even so, one may say, the influence of the ultra-intellectual or supernormal faculties upon our welfare as terrene organisms is less marked in common life than the influence of the organic or subnormal faculties. Yet it is _that_ prolongation of our spectrum upon which our gaze will need to be most strenuously fixed. It is _there_ that we shall find our inquiry opening upon a cosmic prospect, and inciting us upon an endless way. Even the first stages of this progress are long and labyrinthine; and it may be useful to conclude this introductory chapter by a brief summary of the main tracts across which our winding road must lie. It will be my object to lead by transitions as varied and as gradual as possible from phenomena held as normal to phenomena held as supernormal, but which like the rest are simply and solely the inevitable results and manifestations of universal Law. Following then on this first or introductory chapter is one containing a discussion of the ways in which human personality disintegrates and decays. _Alternations of personality_ and hysterical phenomena generally are in this connection the most instructive to us.