See es — ea _—. 
PHYSICAL ann LITERARY. #, 
by fome external force. If we lock up any “a 
moveable object, we truft to find it in the fame 
place; and, if it be miffing, we afcribe 
our lofs to thieves, not to felf-motion in the 
body. Matter, fo far as we can difcover, is 
certainly not endued with thought or volun- 
tary motion; and yet, that it is endued witha 
power of motion in certain ‘circumftances, 
appears to me an extreme clear point. Drop- 
ping a {tone froma high tower, it falls 'to 
the ground without any external impulfe, fo 
‘far as we can difcover. : Here is an effect 
produced, which every one, who has not ftu- 
died philofophy, will attribute to a power in 
the ftone itfelf. One would not hefitate to 
draw this conclufion, fhould the {tone move 
upwards; and yet, fetting afide habit and 
cuftom, it muft be evident, that a ftone can 
as little move downwards as upwards with- 
out a vis motrix. And that this is a juft, as 
well as natural way of thinking, will appear 
by analogy. When a man is in motion, we 
q _ readily afcribe the effect produced to a power 
which he poffeffes, to move his limbs. Why 
_ then do philofophers deny to the ftone, in the 
_ act of falling, the power of beginning motion, 
Bs og y 
ae 
ns 
__ a power which they fo readily afcribe to the 
man? 
