this　assumption。　It　is　therefore　no　fault　in　our　deduction　of　the
  supreme　principle　of　morality；　but　an　objection　that　should　be　made　to
  human　reason　in　general；　that　it　cannot　enable　us　to　conceive　the
  absolute　necessity　of　an　unconditional　practical　law　（such　as　the
  categorical　imperative　must　be）。　It　cannot　be　blamed　for　refusing　to
  explain　this　necessity　by　a　condition；　that　is　to　say；　by　means　of
  some　interest　assumed　as　a　basis；　since　the　law　would　then　cease　to　be
  a　supreme　law　of　reason。　And　thus　while　we　do　not　comprehend　the
  practical　unconditional　necessity　of　the　moral　imperative；　we　yet
  comprehend　its　incomprehensibility；　and　this　is　all　that　can　be　fairly
  demanded　of　a　philosophy　which　strives　to　carry　its　principles　up　to
  the　very　limit　of　human　reason。
  …THE　END…