UNDER THE APPLE-TREES 



always essentially the same. Gravity is the ruling 

 force. But among chemical bodies a new force ap- 

 pears; chemical affinity is here the determining fac- 

 tor. The law of probability plays a secondary part. 

 Spontaneous combustion, for instance, is a molecu- 

 lar accident only in a limited sense. The antecedent 

 conditions may be in a measure accidental, but the 

 chemical reactions that bring about the rise of tem- 

 perature to the point of combustion are not acci- 

 dental; they inhere in the constitution of the ele-^ 

 ments. Life may be of spontaneous and fortuitous 

 origin in the same sense; not a mere chance happen- 

 ing among unrelated bodies, but the continuation of 

 long-antecedent conditions brought about by that 

 mysterious force we call chemical attraction. This 

 force, as it were, gives the elements eyes, and hands, 

 and feet, and power of choice, and determines the 

 line of their activities. Liquid water, without which 

 life could not exist, was contingent upon the chemi- 

 cal union in fixed properties of the two gases, oxygen 

 and hydrogen; accident may have played a part in 

 the meeting of those two gases, but, once met, under 

 the proper conditions, water was bound to appear. 

 The chemical union of oxygen and silica, which 

 forms so large a part of the earth's surface, was pre- 

 determined by the nature of the substances, but the 

 forms of the landscape and the size and the shape 

 of the continents were not in the same sense prede- 

 termined. An entirely different disposition of the 



240 



