328 



SCIENCE. 



[N. S. Vol. XVI. No. 400. 



or, in otliei" words, generalization. To cor- 

 rectly generalize iu geology involves the 

 capacity to hold a vast number of facts in 

 the mind at the same time ; to see them in 

 their length and breadth and thickness; to 

 see them at the same time as large masses 

 and as composed of parts, even to the con- 

 stituent mineral particles and the elements ; 

 to see the principles of physics and chemis- 

 try and mineralogy and biology interlacing 

 through them. Only by holding a multi- 

 tude of facts and principles in one 's mind at 

 the same time can they be reduced to order 

 under general laws. 



Faihare thus to hold in one's mind a 

 large number of facts and principles leads 

 to lack of consistency. Often in a single 

 book or a single chapter, on the same 

 page, or even in the same paragraph or sen- 

 tence, are contained ideas which are exclu- 

 sive of one another. They are not seen by 

 the writer to be exclusive of one another 

 because he is so lacking in a command of 

 the principles of the basal sciences that he 

 is not aware of the antagonism. Major 

 Powell once said to me, ' The stage of the de- 

 velopment of the human mind is measured 

 by its capacity to eliminate the incongru- 

 ous.' If this hard criterion were rigidly 

 applied, it would follow that many of our 

 professions have not passed the youthful 

 stage. The man who can insert in the 

 same treatise, chapter or page incongruous 

 ideas saves an immense amount of cerebral 

 tissue for himself. Such a man can Avrite on 

 through chapters and books, and not find it 

 necessary to go back, adjust and interrelate 

 the various parts. There is no action and re- 

 action between the multitude of ideas. The 

 writer has the easy task of holding in his 

 mind at any one time but a few data. He 

 is in delightful and happy unconsciousness 

 of the fact that many of his statements de- 

 stroy one another. But the man who sees the 

 phenomena and principles of geology in all 

 their complex relations, and tries to express 



the parts of them he is considering in pro- 

 portion to one another, and to place his 

 fragment of the science of geology in proper 

 relations to other departments of geology 

 and other natural sciences, has a task be- 

 fore him requiring great mental effort. 

 He must see and understand in three di- 

 mensions. At every point he must see 

 the lines of cause and effect radiate and 

 converge upon the phenomena he is consid- 

 ering from many other phenomena and 

 principles. Of course all fail to do this 

 completely in reference to any com- 

 plex problem. But in so far as success 

 would be attained, the effort must be made. 

 In proportion as one can hold many facts 

 and principles and see their interrelations, 

 he will be able to advance the philosophy 

 of geology. This is the work which burns 

 the brain. 



And his results he must express in lan- 

 guage, the chief means of communicating 

 ideas and relations. Yet language is linear. 

 By figures, models, maps and illustrations, 

 wisely used, one may to an important de- 

 gree supply the defects of linear language. 

 Yet language and illustration, even where 

 used to the best advantage, but poorly con- 

 vey one 's ideas. Most conscientious writers 

 require as much or more time to put a com- 

 plex subject into words and illustrations 

 ready for publication as they do in working 

 out the results. 



But upon the other side, and in favor of 

 expression in language, it should be re- 

 membered that there is action and reaction 

 between one's ideas and the attempt to ex- 

 press them in words and illustrations. The 

 necessity for expression in language is often 

 a wonderful clarifier of ideas. The ideas 

 are improved by the attempt at expression, 

 and the expression is continually improved 

 as the ideas are enlarged. 



That the difficulty as to expression does 

 not apply to geology alone is well illustrated 

 by the vast amount of labor Charles Darwin 



