These   considerations   make   it   obvious  why  arithmetic  and  geometry
prove  to  be  much  more  certain  than  other  disciplines:  they  alone are
concerned   with   an   object   so  pure  and  simple   that   they   make   no
assumptions that experience  might render uncertain; they consist entirely
in   deducing   conclusions   by   means   of  rational   arguments.  They  are
therefore the easiest and clearest of all the sciences and have just the sort
of  object  we  are  looking   for.   Where  these  sciences  are  concerned  it
scarcely seems humanly  possible to err, except through inadvertence.  Yet
we should  not be  surprised  if many  prefer  of their own  accord  to apply
their  minds  to  other  arts,  or to  philosophy.  The  reason  for this is that
everyone  feels free to  make more  confident  guesses about matters which
are  obscure  than  about  matters  which  are  clear.   It  is  much  easier to
hazard  some  conjecture  on  this  or  that  question  than  to arrive  at the
exact  truth  about  one   particular  question,  however   straightforward it
may be.



Rene Descartes, "Rules for the Direction of the Mind"
(orig. lat. ''Regulae ad directionem ingenii", 1619)