MATTER, MOTION, AND FORCE 



independently of the motion of the whole, we 

 are enabled legitimately to restrict our views, 

 so that motion along the resultant of two or 

 three forces may be determined and predicted 

 with a near approach to accuracy. Witness the 

 ease with which we can calculate the orbit of 

 a comet. But when the forces become more 

 numerous, it becomes impossible to determine 

 their resultant. Witness the excessive difficulty 

 of predicting the direction of currents in the 

 atmosphere. The movements of organisms still 

 more hopelessly baffle our powers of calculation. 

 It is hardly probable that science will ever ob- 

 tain equations for the motions of a lion in se- 

 curing his prey ; yet that would be a very shal- 

 low philosophy which should seek to assure us 

 that each one of those motions does not take 

 place along the resultant of all the forces in- 

 volved. To an intelligence sufficiently vast, the 

 motions of the earth in space would doubtless 

 seem as complicated as those of the lion seem 

 to us. But no amount of complexity can alter 

 the fundamental principle that the direction of 

 motion must be the resultant between the lines 

 of greatest traction and of least resistance. 



In conclusion let us observe that in many 

 cases the total amount of traction is so small 

 compared to the total amount of resistance, that 

 for practical purposes it may be neglected ; and 

 vice versa. Thus, when a meteor falls upon the 



TOL II i£j 



