[ ^^4 ] 



" fancy that, if we were brought oF a fudtkn into this world, we 



" would at firll have inferred that one billiard ball would commu- 



" nicate motion to another upon impulfe — bat the mind can 



" never poflibly find the eifed in the fuppofed caufe by the moft 



" accurate fcrutiny and examination — motion in the fecond bil- 



" Hard ball is quite a dillindt event from motion in the firft, nor 



" is there any thing in the one to fuggeft the fmalleft hint of the 



" other." And, page 301, " When I fee a billiard ball moving in 



" a ftraight line towards another, even fuppofe motion in the other 



" fhould by accident be fuggefted to me, may I not conceive that 



"' a hundred different events might as well follow from ihat caufe ? 



" May not both the balls remain at abfolute reft ? May not the 



*' firft ball return in a ftraight line, or leap off from the fecond in 



" any line or diredion ? All thefe fuppofitions are confiftent and 



" conceivable. Why then fliould we give the preference to one, 



-'■ which is no more confiftent or conceivable than the reft? No 



" reafoning a priori will ever be able to ftiew us any foundation 



" for this preference." 



Now, in oppofition to what is thus fo confidently afferted, I fay, 

 that from a knowledge of a few of the moft -general properties of 

 bodies, a knowledge which is implied in the fuppofition of an at- 

 tejnpt to reafon a priori, the fad of the communication of motion 

 by impulfe may be inferred previous to adual experience of it. 



To 



