Training of a Geologist. — Van Hise. i6i 
book, or a single chapter, or on the same page, or even in the 
same paragraph or sentence, arc contained ideas which are 
exclusive of one another. They are not seen by the writer to 
be exclusive of one another because he is so lacking in a com- 
mand 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 development of the human mind is measured by its 
capacitv to eliminate the incongruous.' If this hard criterion 
were rigidly applied, it would follow that many of our pro- 
fession 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 write on through chapters and books, and not find 
it necessary to go back, adjust and interrelate the various parts. 
There is no action and reaction between the multitude of ideas. 
The writer has the easy task of holding in his mind at any one 
time but a fevv^ data. He is in delightful and happy uncon- 
sciousness of the fact that many of his statements destroy one 
another. But the man who sees the phenomena and principles 
of geology in all their complex relations, tries to express 
the parts of them he is considering in proportion to one another, 
and to place his fragment of the science of geology in prop- 
er relations to other departments of g'eology and other natural 
sciences, has a task before him requiring great mental effort. 
He must see and understand in three dimensions. At every 
point he must see the lines of cause and eft'ect radiate and con- 
verge upon the phenomena he is considering from many other 
phenomena and principles. Of course all fail to do this com- 
pletely in reference to any complex problem. All fail to reach 
the ultimate truth. To do so would require infinite capacity. 
But in so far as success would be attained, the eft'ort must 
be made. In proportion as one can hold many facts and prin- 
ciples 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 language, the chief 
means of communicating ideas and relations. Yet language i« 
linear. By figures, models, maps and other illustrations, wisely 
used, one may to an important degree remed>- the defects of 
linear language. Yet language and illustration, even where used 
