THE SCIENTIFIC IMAGINATION 263 



color-blind man, who has not discerned his defect, 

 has of the nature of color." One scientist confessed 

 that it was only by a figure of speech that he could 

 describe his recollection of a scene as a mental image 

 to be perceived with the mind's eye. 



When Galton questioned persons whom he met in 

 general society he found " an entirely different dispo- 

 sition to prevail. Many men and a yet larger number 

 of women, and many boys and girls, declared that 

 they habitually saw mental imagery, and that it was 

 perfectly distinct to them and full of color." The 

 evidence of this difference between the psychology 

 of the average distinguished scientist and the average 

 member of general society was greatly strengthened 

 upon cross-examination. Galton attributed the differ- 

 ence to the scientist's " habits of highly generalized 

 and abstract thought, especially when the steps of 

 reasoning are carried on by words [employed] as 

 symbols." 



It is only by the use of words as symbols that sci- 

 entific thought is possible. It is through cooperation 

 in work that mankind has imposed its will upon the 

 creation, and cooperation could not have been carried 

 far without the development of language as a means of 

 communication. Were it not for the help of words 

 we should be dependent, like the lower animals, on 

 the fleeting images of things. We should be bound 

 to the world of sense and not have range in the world 

 of ideas. Words are a free medium for thought, for 

 the very reason that they are capable of shifting 

 their meaning and taking on greater extension or in- 

 tension. For example, we may say that the apple falls 

 because it is heavy, or we may substitute synonymous 



