METHOD OF DISCOVERY 53 



to a conclusion as to the course he should take in order 

 to make good a robbery and punish the offender. I say 

 that you are led, in that case, to your conclusion by exactly 

 the same train of reasoning as that which a man of science 

 pursues when he is endeavouring to discover the origin and 

 laws of the most occult phenomena. The process is, and 

 always must be, the same ; and precisely the same mode 

 of reasoning was employed by Newton and Laplace in 

 their endeavours to discover and define 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 hypotheses 

 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 pro- 

 ductive of mischievous, if not fatal, results in the long run. 

 Do not allow yourselves to be misled by the common 

 notion that an hypothesis is untrustworthy simply because 

 it is an hypothesis. It is often urged, in respect to some 

 scientific conclusion, that, after all, it is only an 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 an hypothesis is subjected to the most rigid 

 examination, we may rightly pursue the same course. 

 You may have hypotheses and hypotheses. A man may 

 say, if he likes, that the moon is made of green cheese : 

 that is an 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 probably composed of materials very similar 

 to those of which our own earth is made up : and that 

 is also only an hypothesis. But I need not tell you that 

 there is an enormous difference in the value of the two 

 hypotheses. That one which is based on sound scientific 

 knowledge is sure to have a corresponding value ; and 

 that which is a mere hasty random guess is likely to have 

 but little value. Every great step in our progress in 

 discovering causes has been made in exactly the same 



