CHARLES B. WARRING, PH.D. I3l 



parts of the same molecule have opposite powers of at- 

 traction and repulsion. 



Heat gives another example of physical law. It ex- 

 pands by its presence and contracts by its absence. By 

 its incessant flov7 it tends to bring all things to one tem- 

 perature. By changing the condition as to fixity of 

 molecules, it accelerates in some cases chemical action, 

 and in others, retards it. Within a certain range it is 

 necessary to animal and plant life, beyond that range it 

 destroys life. 



Last of all there is light. Its law^s of refraction, re- 

 flection, and polarization are of no account to the inor- 

 ganic world. The rocks and mountains, seas and plains, 

 although ov^ing so much to heat, owe nothing to the 

 laws of light. But to the vegetable and animal world 

 these are of great importance ; more than that, to them 

 vegetables and animals owe the possibility of existence. 



Thus much for the peculiarities of the various physical 

 laws — points in which they differ. Look now at their 

 common characteristics. First of all is there absolute 

 inviolability. Though not omnipotent they cannot be 

 broken. A moral law we may break. I am commanded 

 to love my neighbor as myself, but I need not do it. 

 Thou shalt not kill, thou shalt not steal, thou shalt not 

 bear false witness, are not merely avoided, or in some way 

 held in abeyance, they are flatly disobeyed every day. 

 But if I walk off a precipice, I do not violate the law of 

 gravitation. I obey it to my sorrow. My broken limbs 

 are painful evidence that the destruction due to the 

 kinetic energy put into them by the fall is exactly pro- 

 portioned to the distance fallen, and the negative energy 

 developed by the sud3.en stoppage is inversely as the 

 square of the time that painful process occupies. Nor can 

 I stay the action of this law. If I pile stones ui)on a table, 

 the table will stand until, at last, the load becomes too 

 great, and then the table is crushed to the floor. But 



