If our analysis is correct, the diseases which affect recognition will be of two widely differingTherefore one kind of psychic blindness may be due to a disturbance of motor habits, not to the loss of memory-images. forms, and facts will show us two kinds of psychic blindness. For we may presume that, in some cases, it is the memory-image which can no longer reappear, and that, in other cases, it is merely the bond between perception and the accompanying habitual movements which is broken,—perception provoking diffused movements, as though it were wholly new. Do the facts confirm this hypothesis?
There can be no dispute as to the first point. The apparent abolition of visual memory in psychic blindness is so common a fact that it served, for a time, as a definition of that disorder. We shall have to consider how far, and in what sense, memories can really disappear. What interests us for the moment is that cases occur in which there is no recognition and yet visual memory is not altogether lost. Have we here then, as we maintain, merely a disturbance of motor habits, or at most an interruption of the chain which unite them to sense perceptions? As no observer has considered a question of this nature, we should be hard put to it for an answer if we had not noticed here and there in their descriptions certain facts which appear to us significant.
The first of these facts is the loss of the sense of direction. All those who have treated the subject of psychic blindness have been struck by this pecu-
