46 " JOHN WESLEY POWELL. 



the discovery of satisfactory theories, classifications are artificial 

 and tentative. 



These interdependencies and others that might be named ren- 

 der it impossible always to discriminate the three kinds of scientific 

 work, and it is still less possible to classify scientific workers under 

 three corresponding heads ; but it is nevertheless true that a large 

 body of workers devote their lives to observation on selected sub- 

 jects and generalise but little; and that others deal chiefly with 

 generalisation and theory. The best observers are acquainted with 

 competing hypotheses as to the phenomena under observation; 

 and the observations of those ignorant of hypotheses are compara- 

 tively worthless. The best theorists are personally familiar with 

 observation ; and the theories of those who are not also observers 

 are unsuccessful. 



It results that the great investigators, those who contribute 

 classifications and theories which are at once comprehensive and 

 stable, are not merely men with great power of generalisation and 

 anatysis, they are also men whose training as observers enables 

 them to sort the good from the bad in the recorded observations of 

 others. The greatest investigators have begun with mere observa- 

 tion, or with the collection of specimens, have then discussed their 

 own observations, and finally in full maturity have reared noble 

 structures of philosophy on foundations far broader than the ob- 

 servation of an individual could compass. 



Powell's early scientific work made no important literary rec- 

 ord. He collected the mammals, reptiles, shells, plants, fossils, 

 and minerals of his region, ascertained their names, and prepared 

 faunal and floral lists, but in this he did little more than follow the 

 tracks of others. Whether consciously or unconsciously, he was 

 training his mind to habits of close observation and establishing an 

 all-important respect for the facts of nature. His contributions to 

 the world's knowledge and the world's philosophy began in later 

 life and pertain to other fields of research. As an explorer he con- 

 tributed to geography, geology, and ethnology; ethnologic study 

 led him to the broader science of anthropology ; and the evening 

 of his life was given to the broadest of all generalisations and the 

 most comprehensive of all theories, a system of philosophy. 



His contributions to physical geography and geology are chiefly 

 contained in three treatises. In his volume on the Exploration of 

 the Colorado River the first part is a narrative of the voyage the 

 narrative quoted in the preceding chapter, and the second part 

 is a systematic account of the physical features of the river val- 



