THE UNFATHOMED UNIVERSE 9 



the simplest manner the motions which take place in Na- 

 ture ". Widening this a little, we may say that the aim 

 of science is to describe natural phenomena and occurrences 

 as exactly as possible, as simply as possible, as completely 

 as possible, as consistently as possible, and always in terms 

 which are communicable and verifiable. This is a very dif- 

 ferent role from that of solving the riddles of the universe, 

 and it is well expressed in what Newton said in regard to 

 the law of gravitation. " So far I have accounted for the 

 phenomena presented to us by the heavens and the sea by 

 means of the force of gravity, but I have as yet assigned 

 no cause to this gravity. ... I have not been able to 

 deduce from phenomena the raison d'etre of the properties 

 of gravity and I have not set up hypotheses " (Newton, 

 Philosophies naturalis Principia Mathematica. 1687). 



"We must confess," said Prof. J. H. Poynting (1900, 

 p. 616), "that physical laws have greatly fallen off in 

 dignity. No long time ago they were quite commonly de- 

 scribed as the Fixed Laws of Nature, and were supposed 

 sufficient in themselves to govern the universe. Now we 

 can only assign to them the humble rank of mere descrip- 

 tions, often erroneous, of similarities which we believe we 

 have observed. ... A law of nature explains nothing, 

 it has no governing power, it is but a descriptive formula 

 which the careless have sometimes personified." It used to 

 be said that " the laws of Nature are the thoughts of God " ; 

 now we say that they are the investigator's formula sum- 

 ming up regularities of recurrence. 



This view of the function of science must be accepted as 

 expressing at least part of the truth, for who should know 

 better what they are aiming at than the great discoverers 

 themselves ? But is it not necessary to make certain reserva- 



