618. It is by considering hallucinations in this generalised manner and among these analogies, that we can best realise their absence of necessary connection with any bodily degeneration or disease. Often, of course, they accompany disease; but that is only to say that the central sensory tracts, like any other part of the organism, are capable of morbid as well as of healthful stimulus. Taken in itself, the mere fact of the quasi-externalisation of a centrally initiated image indicates strong central stimulation, and absolutely nothing more. There is no physiological law whatever which can tell us what degree of vividness our central pictures may assume consistently with health - short of the point where they get to be so indistinguishable from external perceptions that, as in madness, they interfere with the rational conduct of life. That point no well-attested case of veridical hallucinations, so far as my knowledge goes, has yet approached.

It was, of course, natural that in the study of these phantasms, as elsewhere, the therapeutic interest should have preceded the psychological. Men's need to understand themselves has never been so pressing as their need to keep themselves alive and comfortable. In the popular mind the rats and snakes that terrify the drunkard stand, one may say, for the whole category of externalised quasi-percepts; and the plain duty of man seems to be to avoid them. Such a view - still lingering in a modified form even in some scientific circles - must gradually give way to the newer feeling that it is only by gazing long and profoundly into man that we can learn how to improve him in a profound and lasting way; and that it is on man's steady and generic evolution, rather than on his occasional and individual degenerations, that the main thought and effort of science must henceforth be fixed.1 The main use of knowing in what ways the race tends to slip backwards is that we may know how to press it forward instead.

In short, it is a science of eugenics rather than of therapeutics which is the characteristic, the primary science for any living and modifiable race; and for our dawning practical science of eugenics experimental psychology is the indispensable theoretic precursor.

These reflections, I suppose, like many others in this work, will for the present hover, as it were, in men's minds between the paradox and the truism. To turn them definitely into truisms it is, I think, only needful that the study of inner vision should be pursued experimentally by competent persons from its very inception up to the most advanced degree which experimentation can attain. In the meantime I can offer as usual only the vindemiatio prima, the scanty and hasty first ingatherings from an unharvested field.

619. I have spoken of the hallucinations which suggestion can induce, during or after the hypnotic trance, or in some few cases in a subject in the waking condition. With the possibility of such quasi-percepts the world is now familiar, however little attention their true significance may have received. But when we leave these, to what must we next turn? Can this form of experiment be varied and improved upon? Can we get rid of the superfluous and intensify the interesting part?

1 We may say that psychology is passing from the initial state of each science in turn, when the new science depends on observation only without experiment, into the second state when it depends on experiment; but that thus far it remains in that early stage of the second state when the methods of experiment are such as other sciences have suggested, not such as this special branch of inquiry suggests for itself, or can use with unique effect. Thus, for instance, in the study of crystals men began by measuring their external angles. Then they sliced them and found their planes of cleavage; and it seemed as though the crystals had been examined through and through. But with the discovery of the polarisation of light came a more intimate analysis; and we classify the crystal now by the behaviour of the ray within. What we want to get hold of in psychology is some experiment which shall compare with the registry of reflexes and the description of end-organs as the polariscope compares with the goniometer; which shall avail to detect double or multiple refraction within a personality which to less subtle analyses seems still a limpid homogeneous whole.

We have been studying the hallucinatory images generated in obedience to A's suggestion in the mind of the hypnotised B.

Now, in the first place, it is no longer interesting to us that A should have any directing voice in starting the images. It is B's mind that we want to study, and we would rather leave it undisturbed by ordinary verbal suggestion; although, of course, we shall be glad to observe telepathic impact, if we can.

In the second place, it would plainly be more convenient if we could dispense with hypnotisation, and get B to see and describe the hallucinations in his waking state. But can B get at these subliminal pictures by any mere effort of will ? Can he do anything more than simply summon up memory-images and combine them in fantastic ways? Can he get at anything deeper than vague day-dreams or scrappy recollections ? Let us consider whether, apart from such a rare and startling incident as an actual hallucination, there is any previous indication of a habit of receiving, or a power of summoning, pictures from a subliminal store-house? Any self-suggestion, conscious or unconscious, which places before the supraliminal intelligence visual images apparently matured elsewhere ?

Such indications have not been wanting. In the chapter on Genius, in the chapter on Sleep, and in 610 A we have traced the existence of many classes of these pictures; all of them ready, as it would seem, to manifest themselves on slight inducement. Dream-figures will rise in any momentary blur of consciousness; inspirations will respond to the concentrated desire or the mere passing emotion of the man of genius; after-images will recur, under unknown conditions, long after the original stimulus has been withdrawn; memory-images will surge up into our minds with even unwished-for vividness; the brilliant exactness of illusions hypnagogiques will astonish us in the revealing transition from waking to sleep.

All is prepared, so to say, for some empirical short-cut to a fuller control of these subjacent pictures; just as before Mesmer and Puységur all was prepared for an empirical short-cut to trance, somnambulism, suggestibility.

All that we want is to hit on some simple empirical way of bringing out the correlation between all these types of subjacent vision, just as mesmerism was a simple empirical way of bringing out the correlation between various trances and sleep-waking states.