The mysticism which I have hitherto investigated is the incapacity, due to weakness of will, either innate or acquired, to guide the work of the association of ideas by attention, to draw shadowy liminal representations into the bright focal circle of consciousness, and to suppress presentations which are incompatible with those attended to. There exists, however, another form of mysticism, the cause of which is not defective attention, but an anomaly in the sensitivity of the brain and nervous system. In the healthy organism the afferent nerves convey impressions of the external world in their full freshness to the brain, and the stimulation of the brain-cell is in direct ratio to the intensity of the stimulus conducted to it. Not so is the deportment of a degenerate or exhausted organism. Here the brain may have forfeited its normal irritability; it is blunted, and is only feebly excited by stimuli conveyed to it. Such a brain, as a rule, never succeeds in elaborating sharply-defined impressions. Its thoughts are always shadowy and confounded. There is, however, no occasion for me to depict in detail the characteristics of its mental procedure, for in the higher species of the degenerate a blunted brain is hardly ever met with, and plays no part in art or literature. To the possessor of a sluggishly-reacting brain it hardly ever occurs to compose or paint. He is of account only as forming the creative mystic’s partial and grateful public. Inadequate excitability may moreover be a property of the sensory nerves. This irregularity leads to anomalies in mental life, with which I shall deal exhaustively in the next book. Finally, instead of slow reaction there may exist excessive excitability, and this may be peculiar to the whole nervous system and brain, or only to a portion of the latter. A generally excessive excitability produces those morbidly-sensitive natures in whom the most insignificant phenomena create the most astonishing perceptions; who hear the ‘sobbing of the evening glow,’ shudder at the contact of a flower; distinguish thrilling prophecies and fearful threatenings in the sighing of the wind, etc.[83] Excessive irritability of particular groups of cells of the cerebral cortex gives rise to other phenomena. In the affected part of the brain, stimulated either externally or by adjacent stimuli, in other words, by sense impressions or by association, the disturbance does not in this case proceed in a natural ratio to the strength of the exciting cause, but is stronger and more lasting than is warranted by the stimulus. The aroused group of cells returns to a state of rest either with difficulty or not at all. It attracts large quantities of nutriment for purposes of absorption, withdrawing them from the other parts of the brain. It works like a machine which an unskilful hand has set in motion but cannot stop. If the normal action of the brain-cells may be compared to quiet