THE LAWS OF MOTION 53 



world revolved; whether the world was always in its present 

 state; what the stars were; what the sun was. The conclu- 

 sions that he drew were at first very erroneous, as any student 

 of mythology knows. Yet the great thinkers, working from 

 what they learned through history, physics, chemistry, have 

 formulated certain theories which may explain our solar 

 system and its formation. There is hardly a scientist who 

 will have the temerity to say that any given theory is abso- 

 lutely correct, yet all these theories are very reasonable and 

 are supported by such an immense number of facts that they 

 are probably correct to a very great extent. Theories must 

 precede practice, and are very valuable as a starting point 

 for scientific investigation. 



References : 



1. 1002 : 441-443. The Advantages of Theories. 



a. 1701 : 64. Value of a Theory. 



6. 1705 : 89-90. The Necessity of Theories. 



c. 1712 : 7. The Definition of a Hypothesis. 



d. 1801:3. Theory Defined. 



e. 1807 : 145. The Meaning and Value of a Theory. 

 /. 1808: 11. Hypotheses, Theories, Laws. 



g. 1809 : 5-6. The Theoretical Methods of Physics. 



37. THE LAWS OF MOTION 



All heavenly bodies obey the laws of nature in the 

 same way as do small bodies. It may be well to consider 

 what is meant by the law of nature, or, as it is sometimes 

 called, natural law. A man-made law is a rule of conduct; 

 nature's laws, as they are formulated by man, are merely 

 statements of facts. Man has made the discovery that cer- 

 tain results come from certain causes. His discovery does 

 not make nature act that way, for nature has always acted 



