This becomes evident in experiments with liminal stimuli which are stated to be unperceived by the subject ; and yet , if forced to " guess " whether they have been given him or not , the proportion of correct guesses affords statistical evidence of the reality of the experience .sx Unperceived taste experience like sweetness may be caused to be perceived by stimulating another area of the tongue with a solution of salt which is so weak that it alone would also be imperceptible .sx These are laboratory experiments ; but there is also a vast amount of clinical data derived from psychoanalysis which substantiates the view that beneath the normal level of awareness there exist deeper and deeper strata of experience in which processes analogous to those of consciousness take place .sx Such processes are strongly marked by their conative and purposeful character and , though unconscious , play their part in determining the course of consciousness .sx How deeply we may conceive the lowermost strata to lie is a matter for analogical interpretation ; but there is no reason why we should not suppose that the lowest limit is that of intracellular life , or even of the elemental energies themselves .sx All this would be the region of the mental though unconscious self .sx Apart from laboratory experiments and clinical observations , however , the very nature of the field of consciousness suggests the reality of the unconscious .sx Consciousness gradually fades from a central area of maximal clearness , through areas of less and less determinateness and intensity,to a margin or fringe in which clearness is minimal .sx Theoretically the field may be extended to a region in which , by reason of lack of intensity or determinateness , there is no clearness whatever ; and this theoretical extension may be indefinitely prolonged .sx If we represent it by a normal curve , the apex would stand for the focus of the field and the descending and widening curve would picture the decreasing clearness and the increasing area of consciousness .sx At a certain point in the curve we should reach the threshold , beyond which there would no longer be consciousness , but only unconscious experience .sx This is an entirely psychological conception , and does not of itself necessitate any particular view as to the constitution of the body .sx With respect to the interpretation of the phenomena of co-consciousness the notion of a threshold is capital .sx We are conscious of all that arises above the threshold and unconscious of all that fails so to arise .sx But the threshold is not necessarily fixed at one definite point of the curve .sx Its height may vary in different circumstances with consequent shrinkages and enlargements of consciousness .sx In point of fact it varies with every one of us when we gradually lose consciousness as we fall asleep .sx A high threshold means that some of the upper layers of the lower levels of experience are shut out ; a low one permits the experiences of these layers to enter awareness .sx Co-conscious " personalities" , whether pathological or artificial , seem in fact to be due to notable alterations in the level of the threshold , while the functional activity of experience at all levels continues .sx unimpaired .sx In hypnosis the threshold is considerably lowered , and the subject's consciousness is , at least potentially , expanded .sx He is hyperaesthetic , can avail himself of memories inaccessible to him in his normal state as well as of normal memories , and is more sensitive to impulses , moods and emotions .sx When awakened , although his consciousness immediately shrinks , functional activity on the lower level does not cease , as is shown by the fact that he carries out post-hypnotic suggestions .sx In all this the pathological cases resemble the hypnotic ones ; though here the normal threshold is raised in the hysterical condition and restored to a permanently lower level by hypnotic treatment .sx It is not incumbent upon the empirical psychologist to provide more than immediate principles of explanation , or concepts by means of which his data may be grouped and related with one another .sx None the less the concepts of the unconscious and of altering thresholds raise problems with regard to the nature of personality which cannot be overlooked .sx What is this unconscious in itself ; and why does the threshold alter in level ?sx G. 17 .sx NATURE OF THE UNCONSCIOUS .sx It has already been suggested that the experience of which we tend to become aware is the sum of the experiences of all the energy-components of the body , which are built up into systems of higher and higher complexity .sx This experience , in so far as not cognised , is the unconscious ; and it is the analogue of the conscious .sx But are we therefore to conceive the energy-components as monads , each being existent in its own right , experiencing and acting for itself , and possibly in some dim way conscious ; while all are integrated in a pluralistic , though hierarchical , system under a supreme monad which is the conscious self ?sx Such a hypothesis has historical precedent in philosophy , and has recently been advanced again on the strength of the phenomena of alternating and co-conscious personalities .sx But it requires that the personalities , alternating or co-conscious , should actually differ ; that more than one person should constitute the living organism .sx And our examination of the phenomena has shown that this is not the case , and that the term " personality " should never have been used in connection with these phenomena .sx Disturbances of memory , alterations of character , shrinkings and expansions of consciousness , undoubtedly occur , and even to a marked degree ; but that is no evidence upon which a hypothesis contradicting the most certain of all our experiences , that namely of the unity of the self , can be based .sx What is the alternative hypothesis to this ?sx It is the supposition that all the physical components of the individual , systematised by the principle of self-conscious energy which constitutes him a person , should enters not merely into an accidental , but into a substantial union .sx The person is not a collection of entities , but a single and undivided unity .sx Nevertheless , though essentially one .sx substance , at all levels of complexity the elementary components and their resultants remain virtually many .sx A crude indication of this lies in the fact that , though it is not my visual or aural apparatus , but I myself , who see and hear , yet visual experience is provided only by the visual , and auditory experience only by the aural apparatus ; and if either of these should be destroyed neither visual nor auditory experience is further possible .sx Virtually these organs act autonomously , as do all the other organs of the body .sx One may say the same for every individual cell that enters into the constitution of tissues and organs ; and even , if the view of matter as merely energetic is acceptable , of every elementary physical energy-component as well .sx This view brings all the abnormal and pathological phenomena into line with the normal ; and , it is submitted , more satisfactorily than any other accounts for all the phenomena of mental life .sx G. 18 .sx ALTERATIONS IN LEVEL OF THRESHOLD .sx With regard .sx to alterations in the level of the threshold , it can only be said that these in fact occur , whether we can give reasons for their occurrence or not .sx But the shrinkages of consciousness in the morbid conditions of hysteria and its expansions in the abnormal state of hypnosis , taken in conjunction with a number of normal phenomena like the automatisation of once conscious processes in acquired habits which are thereafter performed semi-consciously or even unconsciously , point the way to an exceedingly interesting line of speculation .sx Throughout life we are .sx continually delegating to lower levels of subconsciousness and unconsciousness , to lower centres of purposeful activity , the performance of actions originally fully conscious and fully purposive .sx The more perfectly an action is practised the less it needs guidance by conscious thinking .sx This , and , many similar facts , seem to indicate a law of mental parsimony the operation of which leaves conscious energy free for further advance .sx May this not be a universal law of extreme evolutionary importance ?sx May it not indicate that , at more primitive stages of the development of the race , instinctive behaviour was consciously directed throughout , and became delegated to the unconscious only when conscious energy was needed elsewhere in the service of evolution ?sx May this not have been the history also of purposeful physiological activity even of the most rudimentary kind ?sx May not each stage have been marked by a rising threshold beneath which conscious striving sank in the form of unconscious experience and habit ?sx At the stage human beings have at present reached the normal threshold would have been determined by this process at a level appropriate to our actual development , thus leaving our limited amount of conscious energy available for the practical direction of the affairs of our every-day life ; while previous consciousnesses were registered in the form of stored experience in the organs , cells and elements of our bodies , all of which show evidence of purposeful activity which at least simulates conscious purpose .sx If this were so , we could describe the lowered level of the threshold in hypnosis as the conscious reactivation of a layer of experi- .sx ence which once was but now no longer is consciousness ; while the constricted consciousness of the hysteric would be due to a failure of mental energy and a consequent incapacity on the part of certain experiences to rise above the threshold .sx G. 19 .sx RELATION OF PERSONALITY TO WILL .sx It remains only to summarise the chief features emerging from our examination of personality and to relate them definitely to the human will .sx Personality is an abstract term which denotes the essential constitutive or constitutives of a person .sx It is that in virtue of which an individual is a self-conscious being , with all that self-consciousness implies .sx It is not , however , the fact of being self-conscious which constitutes the person ; for this is a consequence rather than the cause of being one ; it only manifests personality .sx Now , the only person with whom each one of us is in immediate contact , and of whom he has intuitive knowledge , is himself ; and it is precisely in the reflective contemplation of himself that he is self-conscious .sx For the self and its objects alike are known and distinguished from one another in the immediacy of actual living , feeling , knowing and willing .sx Each one of us , moreover , infers other selves , and believes in their existence and essential similarity , on the ground of his experience of them as phenomenal objects and of himself as an apprehended object which is absolutely identical with itself as apprehending subject .sx This , as has been shown , is the fundamental fact of experience ; but , even if it were not so,we should logically be obliged to postulate a subject of experience in order to account for the occurrence of experience at all .sx 20 .sx PRINCIPLE OF PERSONALITY .sx What is it that constitutes an individual as a self-conscious being ?sx Clearly , it is some intrinsic principle which can account for the power of the immediate intuition of the self in its acts which was discussed at length in chapter v. Such a principle , we have argued , is a substance , or actuality existent in itself , which is capable of energising in various ways ; and among the chief of these are cognising , knowing and willing .sx 21 .sx KNOWING .sx Of recent years all the kinds of original knowing have been summed up under three noegenetic principles or laws , which in fact account for the occurrence of all human knowledge .sx Once originated , alterations without doubt occur in our knowledge ; but these are no more than variations in its clearness , together with the disappearance and the recall of items of knowledge which were known before .sx Such processes originate no knowledge ; whereas the processes due to the noegenetic principles do .sx The latter have been enunciated as follows .sx ( I ) Any lived experience tends to evoke immediately a knowing of its characters and experiencer .sx ( 2 ) The mentally presenting of any two or more characters ( simple or complex ) tends to evoke immediately a knowing of relation between them .sx ( 3 ) The presenting of any character together with any relation tends to evoke immediately a knowing of the correlative character .sx These three tendencies towards knowing our experience and ourselves as experiencers , the relations obtaining between the characters or items of our experience , and the items or characters in any way correlated with experience , are at the basis of all our intellectual operations whatever .sx