PHYSICAL AND LITERARY. 87 



its refiftance to motion, are very apt to 

 exprefs themfelves in terms that import 

 a real activity ; and which, if ftridly ua- 

 derftood, are inconfiftent with inertia. 

 Thus, when a perfon in a boat pulls a 

 rope that is fattened to the fhore, it is 

 commonly fald, that the man ads upon 

 the fliore in one diredltion, and that the 

 Ihore, by its readion in the oppofite di- 

 rection, pulls the man and boat towards 

 it. Yet, notwithflanding fuch exprejfli- 

 ons, will any one ferioufly maintain, that 

 the ground has an adive power to pro- 

 duce any fuch eflPed ? It is evidently the 

 force of the man extending himfelf, that 

 draws the fhore with his hands one way, 

 and at the fame time puflies the veffel with 

 equal force with his feet the oppofite way. 

 In like manner, if a perfon ftanding in a 

 boat, pulhes againft the ground with a 

 pole, it is not really the readion of the 

 ground that makes the boat recede ; it is 

 the force of the man that is the only nio- 

 ving power, ading equally upon both 

 the boat and the ground. When a boat 

 is rowed with oars, the oars are faid to 



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