496 H. MAUDSLEY I the sensation be, the conditions of its being are not simple : it is an event the molecular conditions of the occurrence of which are exceedingly complex, more complex than the constitution and motions of the solar system. For what does the structure of the nervous unit of the simple sensa- tion mean ? It means, if I may so speak, nothing less than a most complex and concentrated organic abstract of the general life-relations of all creatures that lived on earth before the level of sensation was reached in the ascending scale of animal existence : a sort of condensed or involuted equivalent of the neurotic pattern or plexus which is organised in the supreme nerve-centres to subserve a par- ticular function but which, instead of being concentrated into a molecule, is there spread over a considerable area. It is impossible, therefore, to stimulate a nervous unit without stirring a multitude of inconceivably minute activi- ties, the quintessential abstract of manifold vital relations with the external world. It is a fair question, however, whether the least pain or sensation would be felt by the individual if we could imagine a nerve-unit iri him to be hurt perfectly separately ; for it might be cogently argued that the condition of pain is the sympathy or synergy of like units to which it is organic neighbour; just, in fact, as the decomposition of a chemical compound is due to sympathy or synergy of similar mole- cules, and could not take place at all were the disturbance limited to one molecule only were it not capable of propa- gating a similar disturbance in neighbouring molecules by the easy infection of similar motions in elements of the same kind. Now if the constitution of the nervous unit have the nature and meaning which I have supposed it to have, it is obvious that when it undergoes stimulation the relations embodied in it as organised or capitalised experience its involuted memories, so to speak are unfolded, as it were, and used. And if the affection of it be of a disorganising or destructive character, as we have reason to think it is when pain is felt, the sensation of pain or suffering is the conscious equivalent of the suffering and shrinking from an unwelcome stimulus which is manifested by the low forms of animal life that possess not any nervous tissue. For it is certain that all forms of living matter exhibit an attraction for that which maintains and fosters their life, and a repulsion to that which lessens and destroys it ; and certain also, one might add, that the nervous system is developed from the same outer layer of the embryo from which the cuticular covering of the body is developed the so-called epiblast or ectoderm.
