METHOD OF DISCOVERY. 67 



same mode of reasoning was employed by Newton 

 and Laplace in their endeavours to discover and de- 

 fine the causes of the movements of the heavenly 

 bodies, as you, with your own common sense, would 

 employ to detect a burglar. The only difference is, 

 that the nature of the inquiry being more abstruse, 

 every step has to be most carefully watched, so that 

 there may not be a single crack or flaw in your 

 hypothesis. A flaw or crack in many of the hy- 

 potheses of daily life may be of little or no moment 

 as affecting the general correctness of the conclusions 

 at which we may arrive; but in a scientific inquiry 

 a fallacy, great or small, is always of importance, and 

 is sure to be constantly productive of mischievous, if 

 not fatal, results in the long run. 



Do not allow yourselves to be misled by the common 

 notion that a hypothesis is untrustworthy simply 

 because it is a hypothesis. It is often urged, in respect 

 to some scientific conclusion, that, after all, it is only 

 a hypothesis. But what more have we to guide us in 

 nine-tenths of the most important affairs of daily life 

 than hypotheses, and often very ill-based ones ? So that 

 in science, where the evidence of a hypothesis is subjected 

 to the most rigid examination, we may rightly pursue 

 the same course. You may have hypotheses and hy- 

 potheses. A man may say, if he likes, that the moon 

 is made of green cheese : that is a hypothesis. But 

 another man, who has devoted a great deal of time 

 and attention to the subject, and availed himself of 

 the most powerful telescopes and the results of the 

 observations of others, declares that in his opinion it is 



