232 THE PRESENT IMPORTANCE OF SCIENCE 



to convince would-be-purchasers of the excellence of his 

 material. An Indian, selecting the proper flint for his arrow- 

 points in the same locality centuries before, might have 

 gone through similar mental processes. 



If we compare the sense of science with the foregoing, the 

 case is as follows : A geologist examines the same rock layer, 

 because of peculiarities which have attracted his attention. 

 He first makes a survey of the entire bed, collecting the fossils 

 and observing structural features, comparing as he does so 

 the present bed with others he has seen. Ripple marks 

 and mud cracks may tell of shallow water, fossils may 

 indicate a marine origin, distorted bedding planes may give 

 evidence of lateral pressure. At last, he classifies the stone, 

 as part of a well known geological horizon, and therefore 

 belonging to a certain period of the earth's history. In 

 such a case, the geologist believes he has reached conclusions 

 obvious to others, and is prepared to take his colleagues over 

 the ground, exhibiting facts and setting forth his inferences. 



The quarryman, did he but know it, goes through similar 

 mental processes; though he is likely to be led astray because 

 his knowledge of rocks is after all limited, and because hope 

 of gain is his main incentive, The advantage possessed by 

 the geologist lies in his broader knowledge and in his desire 

 to establish the facts rather than to make money. The point 

 for us is the parallelism between the mental processes of the 

 two men, which are in essence the inductive method of 

 science. 



Thus the scientific method, like the scientific fact, may be 

 characterized by the adjective common. The facts and 

 methods of science are those which may be shared in common 

 by members of the human species. They are not the whim 

 of one individual, but conclusions reached by individuals, 

 who may be regarded as competent judges in the particular 

 case, and who place similar interpretations upon groupings 

 of sense-impressions past and present. This last does not 

 mean that the mere holding of a belief by a large number of 



