84 PSYCHOLOGY. 



them. A horse's head, a coil of rope, an anchor, are, for 

 example, ideas which have come to me unsolicited whilst I 

 have been writing these latter lines. They can often be 

 explained by subtle links of association, often not at alL 

 But I have not a few times been surprised, after noting 

 some such idea, to find, on shutting my eyes, an after- 

 image left on the retina by some bright or dark object 

 recently looked at, and which had evidently suggested 

 the idea. ' Evidently,' I say, because the general shape,^ 

 size, and position of object thought-of and of after-imag& 

 were the same, although the idea had details which the 

 retinal image lacked. We shall probably never know just 

 what part retinal after-images play in determining the train 

 of our thoughts. Judging by my own experiences I should 

 suspect it of being not insignificant.* 



* The more or less geometrically regular phantasms which are pro- 

 duced by pressure ou the eyeballs, congestion of the head, inhalation of 

 anaesthetics, etc., might again be cited to prove that faint and vague excite- 

 ments of sense-organs are transformed into figured objects by the brain, 

 only the facts are not quite clearly interpretable ; and the figuiing may 

 possibly be due to some retinal peculiarity, as yet unexplored. Beautiful 

 patterns, which would do for wall-papers, succeed each other when the 

 eyeballs are long pressed. Goethe's account of his own phantasm of a 

 flower is well known. It came in the middle of his visual field whenever 

 he closed his eyes and depressed his head, "'unfolding itself and develop- 

 ing from its interior new flowers, formed of coloied or sometimes green 

 leaves, not natural but of fantastic forms, and symmetrical as the rosettes, 

 of sculptors," etc. (quoted in Milller's Physiology, Baly's tr., p. 1397). The 

 fortification- and zigzag-patterns, which are well-known appearances in the 

 field of view in certain functional disorders, have characteristics (steadiness, 

 coerciveness, blotting out of oilier objects) suggestive of a retinal origin — 

 this is why the entire class of phenomena treated of in this note seem to me 

 still doubtfully connected with the cerebral factor in perception of which 

 the text treats. ^I copy from Taine's book on Intelligence (vol. i. p. 61) 

 the translation of an interesting observation by Prof. M. Lazarus, in which 

 the same effect of an after-image is seen. Lazarus himself proposes the 

 name of ' visionary illusions ' for such modifications of ideal pictures by 

 peripheral stimulations (Lehre von den Sinnestituschungeu, 1867, p. 19). 

 " I was on the Kaltbad terrace at Rigi, on a very clear afternoon, and 

 attempting to make out the Waldbruder, a rock which stands out from 

 the midst of the gigantic wall of mountains surrounding it, on whose sum- 

 mits we see like a crown the glaciers of Titlis, Uri-Iiothsdock, etc. I was 

 looking alternately with the naked eye and with a spy-glass ; but could not 

 distinguish it with the naked eye. For the space of six to ten minutes I 

 had gazed steadfastly upon the inountain.s, whose color varied according 



