1 62 The American Geologist. September, 1902 
to the best advantag-e, but poorly convey one's ideas. Most 
conscientious writers require as much or more time to put a 
complex subject into words and illustrations ready for publi- 
cation as they do in working- out the results. 
But upon the other side, and in favor of expression in lan- 
guag;e, it should be remembered that there is action and reaction 
between one's ideas and the attempt to express them in words 
and illustrations. The necessit'y 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 spent in putting into the linear form of language the 
most revolutionary work of the time. 'The Origin of Species.' 
It seemed as if the intricately interrelated facts of life were of 
so coniplex a nature that language could not handle the prob- 
lem. But the genius of Darwin was such that he not only con- 
ceived the idea of natural selection and proved its truth to his 
own mind, but he so marshalled his facts and principles in linear 
form in one volume that men were forced to believe. Many of 
the ideas contained in single sentences or paragraphs of the 
'Origin of Species' have been expanded into papers, volumes or 
treatises by others , and thus made easier to comprehend. The 
'Origin of Species' has often been said to be a difficult book to 
read. So it is, because its ideas are more complex than lan- 
guage can easily convey. Darwin unquestionably saw deeper 
than he was able to express, and it was the struggle to state 
what he knew which made the writing of the 'Origin" such 
an onerous task. But geology as a whole is onlv less complex 
than life ; and many of us in the smaller matters with which we 
are attempting to deal have felt the impossibility of conveying 
more than imperfectly the ideas and relations which are in our 
minds. 
In thinking of the marvelous complexity of the phenomena 
of geology, and seeking for an analog)' which might in some 
measure express this comj^lexitv. it seemed to me that the in- 
habitants of the globe and their intricate relations furnish an 
approximate illustration. From each individual or family or 
hamlet or city or metropolis, there go out on foot, by wheel, by 
