PHYSICAL ann LITERARY. 8 
«© may be defired to reflect on what a perfon 
« feels within himfelf in walking, during 
_ & which’a repeated ativity is exerted to con- 
“ tinue the motion *®.” But this, furely, can 
only be intended as an illuftration of what is 
meant by the fupofed activity of matter in 
motion, and not as a proof of its reality. For, 
every day’s experience muft teach us on the 
contrary, that it requires a great activity, 
fometimes more than we are mafters of, to 
{top a begun motion in our bodies. How 
doth it appear, that the fame effort is necef- 
fary to be continually exerted, which was 
employed at the beginning of the motion? 
We find a certain effort neceffary to begin a 
motion in our own bodies ; but, we fhould 
find no occafion for repeating it, were it not 
confumedor wafted upon other bodies. When 
we give ourfelves one pufh forwards upon a 
{mooth furface, fuch as ice for example, 
there is no need for a fecond immediately ; 
and, were there no attrition nor refiftance 
from the air, the motion would continue for 
: 4 gver. Ifa body fet in motion, were to {top, 
= retard, or any way change, its motion of it- 
ii L felf H 
* Effay I. p. 20, 7 
