THE PERCEPTION OF THINGS 85 



ILLUSIONS. 



Let us now, for brevity's sake, treat A and B in Fig. 47 

 as if they stood for objects instead of brain-processes. And 

 let us furthermore suppose that A and B are, both of them, 

 objects which might probably excite the sensation which I 

 liave called ' this,' but that on the present occasion A and 

 not B is the one which actually does so. If, then, on this 

 occasion ' this ' suggests A and not B, the result is a correct 

 perception. But if, on the contrary, ' this ' suggests B and 

 not A, the result is ?i false perception, or, as it is technically 

 called, an illusion. But the process is the same, whether 

 the perception be true or false. 



to their several altitudes or declivities between violet, brown, and dark 

 green, and I had fatigued myself to no purpose, when I ceased looking 

 and turned away. At that moment 1 saw before me (I cannot recollect 

 whether my eyes were shut or open) the figure of an absent friend, like a 

 corpse. ... 1 asked myself at once how 1 had come to think of my absent 

 friend. — In a few seconds I regained the thread of my thoughts, which 

 my looking for the Waldbruder had interrupted, and readily found that the 

 idea of my friend had by a very simple necessity introduced itself among 

 them. My recollecting him was thus naturally accounted for. — But in 

 addition to this, he had appeared as a corpse. How was this ? — At this 

 moment, whether through fatigue or in order to think, I closed my eyes, 

 and found at once the whole field of sight, over a considerable extent, 

 covered with the same corpse-like hue, a greenish-yellow gray. I thought 

 at once that 1 had here the principle of the desired explanation, and 

 attempted to recall to memory the forms of other persons And, in fact, 

 these forms too appeared like corpses ; standing or sitting, as I wished, all 

 had a corpse-like tint. The persons whom I wished to see did not all ap- 

 pear to me as sensible phantoms ; and again, when my eyes were open. I 

 ■did not see phantoms, or at all events only saw them faintly, of no deter- 

 mined color. — 1 then inquired how it was that phantoms of persons were 

 affected by and colored like the visual field surrounding them, how their 

 outlines were traced, and if their faces and clothes were of the same color. 

 But it was then too late, or perhaps the influence of reflection and exami- 

 nation had been too powerful. All grew siiddenly pale, and the subjective 

 phenomenon, which might have lasted some minutes longer, had disap- 

 peared, — It is plain that here an inward reminiscence, arising in accordance 

 with the laws of as.sociation, had combined with an optical after image. 

 The excessive excitation of the periphery of the optic nerve, I mean the 

 long-continued preceding sensation of my eyes when contemplating the 

 color of the mountain, had indirectly provoked a subjective and durable 

 sensation, that of the complemenatry color ; and my reminiscence, incor- 

 porating itself with this subjective sensation, became the corpse-like phan- 

 tom I have described.' 



