the theory of Darwin and the hypothesis of Laplace, the former is 

 an inference drawn from facts, the latter is an inference drawn from 

 assumptions. The nebular hypothesis has had no more influence 

 on the practice of astronomers, than the so-called atomic theory 

 has had on the practice of chemists. But Darwin's theory of 

 evolution has completely revolutionised the practice of Biologists, 

 as did Newton's theory of gravitation revolutionise the practice of 

 astronomers. The difference between theory and hypothesis is 

 just as great as between fact and opinion, the latter may be true, 

 the former we know is true. Never let us confound science with 

 the opinions of scientific men. 



