Custom has consecrated the word ‘psychical’ facts or phenomena: this term is also imperfect, and it seems to me preferable to adopt the new term Metapsychical which Richet recommends.
Therefore, in the actual state of research, the scientific problem, it seems to me, is not whether spiritism be true or false, but whether metapsychical phenomena be real or imaginary.
As Richet and Ochorowicz have said, every medium may defraud, and the analysis of fraud is one of the most complicated problems which the study of psychical phenomena presents. It is also one of the most interesting. The Cambridge[37] experiments with Eusapia Paladino put clearly before us the question of fraud and its signification.
Before entering upon the psychological examination of fraud, it appears to me necessary to explain the signification of the terms I am going to use, and after that to classify medianic phenomena.
It is of primary importance to determine the correct signification of the expression consciousness.[38] There are few words in philosophical language which have such diverse acceptations. As my conception of consciousness is somewhat special without at the same time being peculiar to me, I owe it to my readers to say what I mean to designate by this term.
I conceive consciousness, lato sensu, as a function of living matter. It is the particular state which determines in organised and living matter another state of the centre where this matter lives. It is, if you like, a kind of reaction of the living matter in harmony with external phenomena. This mode of reaction, like every other mode of reaction, allows of two conditions: some sort of sensibility to the action of the ambient, permitting variations thereof to be felt; some sort of activity which permits of realising an adaptation to the ambient, and of producing internal modifications corresponding, in some measure, to the perceived external modifications. In order that the internal modifications may realise this equilibrium, they must not go beyond a certain amplitude, whence the theoretic necessity for the sensibility to be always apprised of the internal modifications of the living substance, as it perceives the external modifications of the ambient.
Experience proves that in reality things do happen in this way. In fact, we are able in the animal kingdom to prove the existence of special organs, some of them destined to the perception of the successive states of the ambient and of the individual, the others to the active realisation of the latter to the former. The different modifications provoked in the receptive system by the variations of the ambient, determine in their turn the intervention of the active system which realises the internal variations. This is the principle of the nervous and muscular systems, the latter being only put into play by the former; natural history shows us the progressive specialisation of these nervous and muscular elements. At first non-differentiated in appearance, the animal cell presents in more complicated animals a sensitive pole and an active pole, the one nervous, the other muscular. The myo-epithelial or neuro-muscular cells offer us a classical example in the hydra.
The examination of the development of the nervous system and of the muscular system in the vertebrata shows us their growing specialisation. The nervous cells are associated in systems more or less dependent the one upon the other; the muscular cells are accumulated into masses. This is the application of that law of the division of labour, the constant operation of which we observe in all the phenomena of life. The nervous cells are grouped together in a heap, in a nucleus, and send their prolongations to the periphery or to the organs. These prolongations are of two kinds: some transmit impressions towards the cell (dendrites prolongations), others transmit excitations proceeding from the cell (cylindraxes prolongations).[39] The centres themselves are hierarchised, so to speak, and are divided into two wide categories: the first destined to the functions of organic life, circulation, secretions, digestion, etc.; the second to those of the life of relation. These two categories include the sensitive cells and the motor cells; the one transmits to the other the stimulus born of excitations provoked by the internal or external centres.
In superior animals, at any rate in man, we observe that the activity of certain nervous centres is accompanied by a particular phenomenon, which is designated under the name of personal consciousness. It is the notion we have that the phenomenon is perceived by us, that the movement executed is executed by us.
Personal consciousness does not accompany all perceived phenomena, nor all executed movements. Certain given conditions of diverse orders appear necessary, for the consciousness to become aware of these phenomena. This conscious consciousness is translated by the connection of the impression or of the movement with a personality.