620 THE POPULAR SCIENCE MONTHLY. 



Such being the teachings alike of general and of scientific expe- 

 rience, I can not but feel surj)rised that any persons claiming the title 

 of philosophers should affirm that we knoic nothing except matter and 

 motion, and that force is a creation of our own imagination. One 

 might suppose such persons to be either destitute of the " force-sense," 

 or to have based their philosophical system upon the movements of the 

 heavenly bodies which they can only see, instead of upon those mun- 

 dane phenomena in the cognition of which they can bring their hands 

 to the assistance of their eyes. How essential this assistance is to the 

 formation of correct conceptions of the solid forms and relative po- 

 sitions of the objects around us is known to every one who has studied 

 the physiology of the senses. Should we not think it absurd on the 

 part of any one who possesses in the use of his hands the means of de- 

 tecting the error of his visual perceptions, if he were to base a super- 

 structure of reasoning— still more to found a whole system of philoso- 

 phy — upon the latter alone ? Yet such appears to me to be the posi- 

 tion of those who deny our direct cognition of force. 



Let us suppose (if possible) a man who had enjoyed the full use of 

 his eyes, but whose limbs had been completely paralyzed from infancy, 

 looking on at a game of billiards. He would see a succession of mo- 

 tions connected by regular sequence — the motion of the arm of the 

 player, the stroke of the cue, the roll of the ball, its contact with 

 another ball, the movement of the second ball, the change of direction 

 or the entire stop of the first, the rebound of balls from the cushion 

 in altered directions, and so on. And he might frame a statement in 

 " teiTns of motion " of all that passes before his eyes, thinking this all 

 he can know. But suppose the limbs of such a man to be suddenly 

 endowed with the ordinary powers of sensation and movement ; let 

 him take the cue into his hands and himself strike the ball ; let him 

 hold his hand on the table so that the rolling ball shall strike it and 

 make him feel its impact ; let him hold the second ball and feel the 

 shock imparted to it by the stroke of the first. Can any one deny 

 that he would thus acquire a dynamical conception linking together 

 the whole succession pf phenomena, which he was previously quite 

 incapable of forming ; that this dynamical conception is quite as di- 

 rectly based upon the experience derived through his " force-sense " as 

 his kinetic expression was upon that derived through his visual sense ; 

 and that this cognition of the force producing the motions is, there- 

 fore, fully as much entitled to be introduced into a logical doctrine of 

 causation as the visual cognition of the motions themselves ? If it be 

 replied that we have no proof that the movement of the ball we strike 

 is produced by the force which we consciously exert in striking it, I 

 simply rejoin that we have as much proof of it as we have of anything 

 which rests upon universal experience, and which we can verify experi- 

 mentally as often as we choose to try — quite as much as we have of 

 the existence of anything whatever that is external to ourselves. 



