Subjective Sensations and Illusions. 819 



front of him as really as if the friend were there. Evidently in such 

 case the machinery is worked backwards. We saw in the last chapter, 

 examples of this backward motion in hypnotic subjects, where they are 

 caused to take on particular mental or emotional states, by being 

 made to assume the postures and muscular movements which those 

 emotional states ordinarily lead to, and which are expressive of them. 

 So, too, it is worked backward when the operator says to the subject 

 in a serious and alarmed tone, " See that bear ! " The sensation ex- 

 perienced by the subject is the same as if the bear were actually in 

 front of him, and it is a true case of illusion. It is presupposed that 

 the subject has seen a bear in reality and therefore has the organs made 

 by bear stimulations coming through the eye up the optic nerve. These 

 organs are restimulated by what the operator says, the stimulation pass- 

 ing from the auditory sense indirectly to the sight memory organs. 

 Thus, these which are the last in the sight series are the first to be affected 

 by this stimulation. If it goes further, it must be towards the optic 

 nerve, and the retina of the eye, that is, backwards. An illusion of 

 seeing might be created in the brain when the eyes are closed. But 

 there is reason to believe, as we shall see, that the illusion may traverse 

 backwards down the optic nerve and retina, and be projected into the 

 space be^yond. 



Those illusions of the cerebral organs which cannot be represented as 

 simple sensory pictures, are called delusions. The greater part of our 

 ideas and opinions, when acting absolutely alone and not co-ordinated or 

 limited by others, become delusions ; which is due to the fact that there 

 are no independent and unrelated objects in the universe from which we 

 get our stimulations. 



Sir Isaac Newton, from long and earnest attention to the study of 

 light and the spectrum of sunlight, produced such an effect on his brain 

 that for several months the spectrum appeared to him whenever he be- 

 gan to think about it, even in the dark. 



From the subjective nature of an illusion, the same spectre is never 

 seen by more than one person, except in those cases in which there is a 

 real object associated with the spectral illusion and forming a basis or 

 nucleus for it ; as, for example, the case of the ghost of the sea cook, 

 seen by a whole ship's company, in chapter 72. 



Violent stimulations are apt to erect in our internal senses, organs of 

 extreme sensibility which are liable to undue and abnormal excitement 

 upon being restimulated, and which easily become stimulated, especi- 

 ally when, through disease or general weakness, the rest of the organs 

 are not strong enough to counteract and contradict it. A lady, < 'hav- 

 ing been frightened in childhood by a black cat which sprang out from 

 beneath her pillow, just as she was laying her head upon it, was ac- 



