PROGKESSIVENESS OF SCIENCE. 55 



in this section, which was the small number of 

 scientific generalisations of the first magnitude. 



What, some one may indignantly ask, what of the 

 atomic theory, the periodic law, the kinetic theory 

 of gases, the mechanical theory of heat, the un- 

 dulatory theory of light, the cell-theory, Weber's law, 

 and so on ? To which we would answer that while 

 these are doubtless of importance, they lack the 

 generality and the intellectual influence of the four 

 great generalisations already mentioned the in- 

 destructibility of matter, the conservation of energy, 

 the formula of gravitation, and the theory of organic 

 evolution. What impresses one then is, that scientific 

 generalisations of the first magnitude are few, and 

 therefore that the scope for progressive science has 

 at present no visible boundaries. 



FACTORS IN FURTHER PROGRESS. 



(a) Growing Intensity of the Scientific Mood. 

 It cannot be doubted that serious scientific study is 

 now common in circles where half a century ago it 

 was rare; this means an increasing body of observ- 

 ers, critics, and formulators. It is also certain that 

 scientific methods are now being applied to orders of 

 phenomena which half a century ago were observed 

 and discussed in a very easy-going and light-hearted 

 fashion. Some one has said rather bitterly that 

 every science must pass through three periods: of 

 presentiment or of faith, of sophistry, and of sober 

 research ; but it may be confidently asserted that most 

 departments of science have now entered upon the 

 third period. 



It is not long since comparative psychology was, 

 



