ideational and E a sensory centre. F represents a volition and C an inhibited reflex or other spontaneous action, and the dotted line AB an inhibited transmission of stimulus to the motor centre, or at least its inefficiency. AE represents the possible, and perhaps very frequent, immediate and non-deliberative connection between sensation or emotion and a volition, which may be interrupted by the passage of a stimulus through an ideational centre.
Fig. 2.
Now if the motor reaction of A be the inevitable effect of a stimulus at B, transmitted directly through AB, we should never have anything but reflexes of the type AC. But if this effect does not invariably occur we have actions of a different order. AC gets its necessary character from its direct connection with a real or supposed external cause. If that connection is interrupted and internal agencies awakened which weigh alternatives we have a set of initiatives which are not only internal, but also decide for or against a given action according to a law of final causes or ends rather than purely efficient causes. That connection is interrupted by every process involving consciousness of the higher kind, or the activity of ideational centres. How then can the transmission of stimulus along the line AB be prevented and the initiation of volition not only changed, but also made a product of real or possible deliberation? We answer that at least one means to this result is the function of inhibition, which we proceed to examine, and whose importance in this connection will be apparent upon the discovery of its tendency to set aside the reflexes and to produce a mental equilibrium which will be disturbed only by internal and ideational influences.
Mr. Ferrier remarks that "the primordial elements of the volitional actions of infants, and also of adults, are capable of being reduced to reaction between the centres of sensation and those of motion." But he then adds that "besides this power
