38 THE METHOD OF SCIENCE 



kind in general to interpret nature in that systematic way that 

 constitutes science. 



68. The scientific value to us of a fact depends, first, on our 

 power to verify it, to make ourselves and other people sure that it 

 is a fact ; and, second, on our power to classify it, to recognize its 

 relations to other bodies of verified evidence. All classification is, 

 in essence, a process of reasoning, of interpreting. If, armed with 

 a note-book, I went into the world and jotted down accurate state- 

 ments concerning the individual animals and plants I happened 

 to meet, my collection of facts would not constitute science. But 

 if, with their help, I were able to classify living beings into species, 

 orders, genera, and kingdoms, my facts would become, what they 

 were not before, foundations of science. During the process of 

 classification, as I passed from individuals to varieties, and from 

 the latter to species, and so on, my descriptions would become 

 more and more brief, simple, and generalized. Instead of describ- 

 ing many individuals I would describe a single variety ; instead of 

 describing many varieties, I would describe a single species, and so 

 on. But, since a knowledge of species involves a knowledge of 

 varieties, which, in turn, involves a knowledge of individuals, each 

 step in this simplification, this classification, would involve the 

 manipulation of larger and more complex masses of facts, and, 

 therefore, more complex thinking. But, as long as my facts were 

 properly verified and classified, neither they nor the processes of 

 thought involved would grow any the less, or more, scientific for 

 being more complex. If, from the data I had gathered, I were 

 able to formulate a theory of evolution, I should classify an 

 immense body of facts in a new way that would involve very far- 

 reaching and complex thought. 



69. Obviously, however, the complexity of the mental processes 

 involved in classification does not depend wholly, or even mainly, 

 on the number of facts to be classified ; for, however numerous the 

 facts, their relations may be apparent on the surface. In many 

 cases, we have only to discover the facts, and they fall, by them- 

 selves as it were, into the right categories. Thus in anatomy, 

 though the mass of facts is large, and the discovery of some of 

 them may be difficult, it is comparatively easy to describe the 

 bones, ligaments, nerves, and the rest, and state their anatomical 

 relations. It is different with such a study as heredity. Here the 

 relations between the facts are not easy to trace, and the mental 

 processes involved in classification are correspondingly complex 

 and subtle. Thus, suppose a strong and athletic man, who has 



