Page:Mind (Old Series) Volume 12.djvu/334

 No. 47.] [JULY, 1887. MIND A QUARTERLY REVIEW OF PSYCHOLOGY AND PHILOSOPHY. I. THE PEKCEPTION OF SPACE. (III.) 1 By Professor WILLIAM JAMES. 4. Visual Space. IT is when we come to analyse minutely the conditions of visual perception that difficulties arise which have made psychologists appeal to new and quasi - mythical mental powers. But I firmly believe that even here exact investi- gation will yield the same verdict as in the cases studied hitherto. This subject will close our survey of the facts, and if it give the result I foretell, we shall be in the best of positions for a few final pages of critically historical review. If a common person is asked how he is enabled to see things as they are, he will simply reply by opening his eyes and looking. This innocent answer has, however, long since been impossible for science. There are various para- doxes and irregularities about what we appear to perceive under seemingly identical optical conditions, which imme- diately raise questions. To say nothing now of the time- honoured conundrums of why we see upright with an inverted retinal picture, and why we do not see double ; and to leave aside the whole field of colour-contrasts and 1 Continued from MIND Nos. 45, 46. 521