24 PROGRESS OF SCIENCE IN THE CENTURY. 



error, he would confirm his conclusion by control ex- 

 periments with normal animals. The above case 

 illustrates a combination of the method of exclusion 

 with the use of control experiments. 



(/) Formulation and Incorporation. — The final 

 step is to sum up what has been attained in terms 

 as clear and terse as possible, and to add the dis- 

 covery to what has been already established. The 

 digested data are absorbed into the body of science. 

 If the discovery is one of magnitude it will be expres- 

 sible as a formula, which should have the criterion 

 of universal validity in the minds of all who are able 

 to estimate the evidence. But even here, in our 

 judgment, there should arise the final question of 

 considering how the new generalisation consists with 

 others, or in wider terms, how it is related to the 

 sum of human experience. Should it be markedly 

 inconsistent, as the evolution-formula seemed at first 

 to so many, there may be need for re-consideration. 

 The body may have to adapt itself — possibly not 

 without pain — to its new food. 



Finally, to quote once more from Prof. Karl Pear- 

 son : " The scientific method is marked by the fol- 

 lowing features: — (a) careful and accurate classi- 

 fication of facts and observation of their correlation 

 and sequence; (h) the discovery of scientific laws 

 by aid of the creative imagination; and (c) self- 

 criticism and the final touchstone of equal validity 

 for all normally constituted minds.'' 



