178 INTRODUCTION TO PHILOSOPHY OF SCIENCE 



the logical analyses. The former exhibit the general setting 

 of the act, the emotional factors presumably responsible for 

 its occurrence, and the stages into which it seems to break 

 up; the latter attempt to show the technique of discovery 

 and the principles of thought upon which it is based. 



PSYCHOLOGY OF DISCOVERY 



Graham Wallas x analyzes the act of discovery into four 

 stages which he calls Preparation, Incubation, Illumination, 

 and Verification. The first stage is one of "hard, conscious, 

 systematic, and fruitless analysis of the problem." 2 It in- 

 cludes the entire process of intellectual education — acquiring 

 facts, collecting and arranging them, memorizing them, 

 developing critical attitudes of mind, and so on. It is the 

 stage of tiring labor without the rewarding consciousness of 

 progress. The second stage is essentially negative in that it 

 involves "voluntary abstention from conscious thought on 

 any particular problem"; it may be spent "either in con- 

 scious mental work on other problems, or in a relaxation 

 from all conscious mental work." 3 Many scientists, for 

 example, obtain the proper diversion by immersion in detec- 

 tive stories; others by vigorous exercise, such as a brisk 

 walk or a game of tennis. The third stage is less directly 

 under control. Usually the idea occurs as a sudden flash, 

 totally without antecedents in consciousness. There is some 

 justification, however, for believing that it is the culmination 

 of a successful train of association, which has itself been 

 preceded by innumerable unsuccessful trains. The immediate 

 antecedents of the flash of insight may often be discovered 

 by careful introspective analysis. James 4 says that "every 

 definite image in the mind is steeped and dyed in the free 

 water that flows around it. With it goes the sense of its 

 relations, near and remote, the dying echo of whence it came 

 to us, the dawning sense of whither it is to lead." It is often 

 preceded by an intimation of its forthcoming appearance. 



1 Art of Thought (New York: Harcourt, Brace, 1926), Chap. IV. 



2 Ibid., p. 81. 3 Ibid., p. 86. 

 * Principles of Psychology (New York: Holt, 1904), Vol. I, p. 255. 



