50 FSTCHOLOOT. 



cases of extensive iujury about the fronto-temporal regions, 

 as a complication of aphasic disease. Notliuagel suggests 

 tliat whilst the Cimeus is the seat of optical sensationi^, the 

 other 2)arts of the occipital lobe may be the field of optical 

 memories and ideas, from the loss of which mental blind- 

 ness should ensue. In fact, all the medical authors speak 

 of mental blindness as if it must consist in the loss of visual 

 images from the memory. It seems to me, however, that 

 this is a psychological misapprehension. A man whose 

 power of visual imagination has decayed (no unusual phe- 

 nomenon in its lighter grades) is not mentally blind in 

 the least, for he recognizes perfectly all that he sees. On 

 the other hand, he may be menially blind, with his optical 

 imagination well preserved ; as in the interesting case pub- 

 lished by Wilbrand in 1887.* In the still more interest- 

 ing case of mental blindness recently published by Lissauer,t 

 though the patient made the most ludicrous mistakes, call- 

 ing for instance a clothes-brush a pair of spectacles, an um- 

 brella a plant with flowers, an apple a portrait of a lady, etc. 

 etc., he seemed, according to the reporter, to have his men- 

 tal images fairly well preserved. It is in fact the momen- 

 tary loss of our non-optical images which makes us mentally 

 blind, just as it is that of our ?ion-auditory images which 

 makes us mentally deaf. I am mentally deaf if, heainng a 

 bell, I can't recall how it looks; and mentally blind if, see- 

 ing it, I can't recall its souTid or its name. As a matter of 

 fact, I should have to be not merely mentally blind, but 

 stone-blind, if all my visual images were lost. For although 

 I am blind to the right half of the field of view if my 

 left occipital region is injured, and to the left half if my 

 right region is injured, such hemianopsia does not deprive 

 me of casual images, experience seeming to show that 

 the unaffected hemisphere is always sufficient for pro- 

 duction of these. To abolish them entirely I should have 

 to be deprived of both occijDital lobes, and that would de- 

 prive me not only of my inward images of sight, but of my 



* Die Seelenblindheit, etc., p. 51 ff. The meutal blindness was in 

 this woman's case moderate in degree. 

 t Archiv f. Psychiatrie, vol. 21, p. 223. 



