117. But turning back once more to the physical side of our simile, we observe that our knowledge of the visible solar spectrum, however minute, is but an introduction to the knowledge which we hope ultimately to attain of the sun's rays. The limits of our spectrum do not inhere in the sun that shines, but in the eye that marks his shining. Beyond each end of that prismatic ribbon are ether-waves of which our retina takes no cognisance. Beyond the red end come waves whose potency we still recognise, but as heat and not as light. Beyond the violet end are waves still more mysterious; whose very existence man for ages never suspected, and whose intimate potencies are still but obscurely known. Even thus, I venture to affirm, beyond each end of our conscious spectrum extends a range of faculty and perception, exceeding the known range, but as yet indistinctly guessed. The artifices of the modern physicist have extended far in each direction the visible spectrum known to Newton. It is for the modern psychologist to discover artifices which may extend in each direction the conscious spectrum as known to Plato or to Kant. The phenomena cited in this work carry us, one may say, as far onwards as fluorescence carries us beyond the violet end.

The "X rays" of the psychical spectrum remain for a later age to discover.

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.

118. Even the first stages of this progress are long and labyrinthine; and it may be useful to conclude this introductory chapter by a brief sketch 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.

Our inquiry will naturally begin by discussing the subliminal structure, in disease or health, of those two familiar phases of human personality, ordinary waking and ordinary sleep. I shall go on to consider in what way the disintegration of personality by disease is met by its reintegration and purposive modification by hypnotism and self-suggestion. By that time enough will have been said of subliminal phenomena in general to make it possible to deal with their various groups in separate fashion. I shall go on, then, to their mode of automatic manifestation, and first (Chapter VI (Sensory Automatism).) to the sensory automatism which is the basis of hallucination. This includes phenomena claiming an origin outside the automatist's own mind. It will be found that that origin is often to be sought in the minds of other living men; and various forms of telepathy will be brought under review. The conception of telepathy is not one that in its nature need be confined to spirits still incarnate; and we shall find evidence (Chapter VII (Phantasms Of The Dead).) that intercourse of similarly direct type can take place between discarnate and incarnate spirits.

The remainder of the book will discuss the methods and results of this supernormal intercourse.

This scheme will be developed in a series of chapters whose general drift and connection I am anxious that the reader should clearly grasp before he studies them in detail.

119. My second chapter may at first sight appear to stray somewhat far from my main purport. It is of the evolution of human personality that this work proposes to treat; - of faculties newly dawning, and of a destiny greater than we know. Yet I must begin with a detailed discussion of certain modes of that personality's disintegration and decay. The extreme instances of such decay - actual imbecility or insanity - do indeed lie outside my province. But there are many cases where there is no actual insanity, - probably no organic disease of the brain, - but in which nevertheless there are disturbances of personality which teach us more than any theoretical treatise can do as to that complex structure or synergy which it is our object to upbuild or to develop. Alternations of personality and hysterical phenomena generally are in fact spontaneous experiments of precisely the type most instructive to us. For my own argument, indeed, I urgently need some true conception of the psychological meaning of hysteria, - a vague range of phenomena called by a meaningless name; - and when that conception has been reached, the support which it gives by analogy to my own principal thesis will be found to be of the most striking kind.

For in hysteria (as my second chapter will show) we have before us a contraction, an effacement of the spectrum of consciousness, which leaves the hysteric occupying much the same position relatively to ourselves as our own supraliminal consciousness occupies (in my view) relatively to our whole self. Or, to return to our other metaphor: - the essence of hysteria is an instability of the thresholds of consciousness and of voluntary movement, - insomuch that many perceptions which should be fully conscious are for the time submerged, and many actions or motor syntheses which should be subject to waking will have sunk out of that will's control. Occasionally, indeed, and as a sort of incident of the general disturbance, some faculties habitually submerged may rise into apprehension, and there may thus be at some points an analogy between hysteria and genius. But on the whole these two conditions are fundamentally opposed; genius consisting (as we shall presently see) in an intensification of the conscious spectrum, - hysteria in its dimming and interruption by dark belts of anaesthesia and aboulia, - defect of perception and of will; - genius consisting in the uprush of subliminal faculty, - hysteria in the descent and disappearance of faculty which should be supraliminal into depths from which it cannot voluntarily be recalled.