478 SCIENCES OF THE EARTH 



tact zone, but thinning away into tenuous speculation in the outer 

 regions. For myself, I like to think of the nucleus as solid and firm 

 throughout, not as a thin fractured crust floating on a fiery liquid 

 of Plutonian suggestiveness. I like to think of the philosophic and 

 speculative atmosphere as no mere gas-zone of shallow depth, as of 

 old, but as an envelope of intense kinetic life wherein the logical 

 molecules touch one another with marvelous frequency, and wherein 

 there is frictional contact with the solid but seemingly inert litho- 

 sphere. In the outer tenuous zone, indeed, the molecular flights are 

 freer and the excursions are without assignable limits. I believe an 

 appropriate atmosphere of philosophy is as necessary to the whole- 

 some intellectual life of our sciences as is the earth's physical atmo- 

 sphere to the life of the planet. None the less, it must ever be our 

 endeavor to reduce speculation to philosophy, and philosophy to 

 science. For the perpetuation of the necessary philosophic atmo- 

 sphere, we may safely trust to the evolution of new problems concur- 

 rently with the solution of the old. 



But granting the importance of the philosophic element, we doubt- 

 less agree without hesitation that the solid products of accurate and 

 complete observation, natural or experimental, are the bed-rock of 

 our group of sciences. The first great object sought by laudable 

 methods is, therefore, the promotion of the most accurate, searching, 

 exhaustive, and unbiased observation that is possible. One of the 

 earliest efforts in behalf of our sciences, therefore, was naturally 

 directed to the task of promoting the best observational work. It was 

 soon discovered that two chief dangers threatened the worker. bias 

 and incompleteness. To guard against the first there was evolved 



The Method of Colorless Observation 



Under its guidance, the observer endeavors to keep his mind scru- 

 pulously free from prepossessions and favored views. However 

 tensely he may strain his observing powers to see what is to be seen, 

 he seeks solely a record of facts uncolored by preferences or preju- 

 dices. To this end, he restrains himself from theoretical indulgence, 

 and modestly contents himself with being a recorder of nature. He 

 does not presume to be its interpreter and prophet. At length, in 

 the office, he gathers his observations into an assemblage, with such 

 inferences and interpretations as flow from them spontaneously, but 

 even then he guards himself against the prejudices of theoretical 

 indulgence. 



Laudable as this method is in its avoidance of partiality, it is none 

 the less seriously defective. No one who goes into the field with a 

 mind merely receptive, or merely alert to see what presents itself, how- 

 ever nerved to a high effort, will return laden with all that might be 



