THE EXPLANATION OF LAWS 93 



which, as we have seen, implies a law), on the notion of 

 the succession of events in time and the separation of 

 bodies in space and so on. But science has abandoned 

 almost all the theories of pre-scientific days. For there 

 were and are such non-scientific theories ; and it is 

 because the plain man has theories of his own, just as 

 much as the most advanced man of science, that it has 

 not been necessary to occupy a larger space in explaining 

 exactly what a theory is ; the reader will probably 

 have recognized at once something familiar in the kind 

 of explanation which the dynamical theory of gases 

 offers. The most typical theories of the pre-scientific 

 era were those which explained the processes occurring in 

 nature by the agencies of beings analogous to men gods, 

 fairies, or demons. The " Natural Theology " of the 

 eighteenth century which tried to explain nature in 

 terms of the characteristics of a God, known through 

 His works, was a theory of that type ; in the features 

 which have been described as essential to theories it 

 differed in no way from that which we have discussed. 

 But all such theories have been abandoned by science ; 

 the theories that it employs are of a type quite unknown 

 before the seventeenth century. 1 In respect of theories 

 science has diverged completely from common sense ; 

 and the divergence can be traced accurately to the 

 work of a few great men. Common sense is therefore 

 more ready to accept theories rather than laws as the 

 work of individual genius. 



But while I accept fully the view that the formulation 

 of a new theory, and especially of a new type of theory, 



1 An exception is often made in favour of Lucretius, who wrote 

 about 70 B.C. But my own opinion is that moderns, with their fuller 

 knowledge, read into his works ideas which never entered the head 

 of their author. I do not think that (as Mr. Wells maintains in his 

 " Outline of History ") it was merely the barrenness of the soil on which 

 his seed fell that prevented it blossoming into fruit. The sterility of 

 his ideas, contrasted with those of Galileo and Newton, was inherent 

 in them. 



