Mechanical  phenomena  are  by  their  nature  more
Its  nature.  particular,  more  complicated,  and  more  concrete,  than
geometrical  phenomena.  Therefore  they  come  after  geometry  in
our  survey ;  and  therefore  must  they  be  pronounced  to  be  more
difi&cult  to  study,  and,  as  yet,  more  imperfect.  G-eometrical  ques-
tions are  always  completely  independent  of  Mechanics,  while  me-
chanical questions  are  closely  involved  with  geometrical  considerar
tions, — the  form  of  bodies  necessarily  influencing  the  phenomena
of  motion  and  equilibrium.  The  simplest  change  in  the  form  of  a
body  may  enhance  immeasurably  the  difiiculties  of  the  mechanical
problem  relating  to  it,  as  we  see  in  the  question  of  the  mutual
gravitation  of  two  bodies,  as  a  result  of  that  of  all  their  molecules ;
a  question  which  can  be  completely  resolved  only  by  supposing  the
bodies  to  be  spherical ;  and  thus,  the  chief  difficulty  arises  out  of
the  geometrical  part  of  the  circumstances.
Our  tendency  to  look  for  the  essences  of  things,' instead  of  study-
ing concrete  facts,  enters  disastrously  into  the  study  of  Mechanics.
