only　on　that　maxim　whereby　thou　canst　at　the　same　time　will　that　it
  should　become　a　universal　law。
  Now　if　all　imperatives　of　duty　can　be　deduced　from　this　one
  imperative　as　from　their　principle；　then；　although　it　should　remain
  undecided　what　is　called　duty　is　not　merely　a　vain　notion；　yet　at
  least　we　shall　be　able　to　show　what　we　understand　by　it　and　what
  this　notion　means。
  Since　the　universality　of　the　law　according　to　which　effects　are
  produced　constitutes　what　is　properly　called　nature　in　the　most
  general　sense　（as　to　form）；　that　is　the　existence　of　things　so　far
  as　it　is　determined　by　general　laws；　the　imperative　of　duty　may　be
  expressed　thus：　Act　as　if　the　maxim　of　thy　action　were　to　become　by
  thy　will　a　universal　law　of　nature。
  We　will　now　enumerate　a　few　duties；　adopting　the　usual　division　of
  them　into　duties　to　ourselves　and　ourselves　and　to　others；　and　into
  perfect　and　imperfect　duties。*
  *It　must　be　noted　here　that　I　reserve　the　division　of　duties　for　a
  future　metaphysic　of　morals；　so　that　I　give　it　here　only　as　an
  arbitrary　one　（in　order　to　arrange　my　examples）。　For　the　rest；　I
  understand　by　a　perfect　duty　one　that　admits　no　exception　in　favour　of
  inclination　and　then　I　have　not　merely　external　but　also　internal
  perfect　duties。　This　is　contrary　to　the　use　of　the　word　adopted　in　the
  schools；　but　I　do　not　intend　to　justify　there；　as　it　is　all　one　for　my
  purpose　whether　it　is　admitted　or　not。
  1。　A　man　reduced　to　despair　by　a　series　of　misfortunes　feels　wearied
  of　life；　but　is　still　so　far　in　possession　of　his　reason　that　he　can
  ask　himself　whether　it　would　not　be　contrary　to　his　duty　to　himself　to
  take　his　own　life。　Now　he　inquires　whether　the　maxim　of　his　action
  could　become　a　universal　law　of　nature。　His　maxim　is：　〃From
  self…love　I　adopt　it　as　a　principle　to　shorten　my　life　when　its　longer
  duration　is　likely　to　bring　more　evil　than　satisfaction。〃　It　is
  asked　then　simply　whether　this　principle　founded　on　self…love　can
  become　a　universal　law　of　nature。　Now　we　see　at　once　that　a　system
  of　nature　of　which　it　should　be　a　law　to　destroy　life　by　means　of
  the　very　feeling　whose　special　nature　it　is　to　impel　to　the
  improvement　of　life　would　contradict　itself　and；　therefore；　could
  not　exist　as　a　system　of　nature；　hence　that　maxim　cannot　possibly
  exist　as　a　universal　law　of　nature　and；　consequently；　would　be
  wholly　inconsistent　with　the　supreme　principle　of　all　duty。
  2。　Another　finds　himself　forced　by　necessity　to　borrow　money。　He
  knows　that　he　will　not　be　able　to　repay　it；　but　sees　also　that　nothing
  will　be　lent　to　him　unless　he　promises　stoutly　to　repay　it　in　a
  definite　time。　He　desires　to　make　this　promise；　but　he　has　still　so
  much　conscience　as　to　ask　himself：　〃Is　it　not　unlawful　and
  inconsistent　with　duty　to　get　out　of　a　difficulty　in　this　way？〃
  Suppose　however　that　he　resolves　to　do　so：　then　the　maxim　of　his
  action　would　be　expressed　thus：　〃When　I　think　myself　in　want　of　money；
  I　will　borrow　money　and　promise　to　repay　it；　although　I　know　that　I
  never　can　do　so。〃　Now　this　principle　of　self…love　or　of　one's　own
  advantage　may　perhaps　be　consistent　with　my　whole　future　welfare；
  but　the　question　now　is；　〃Is　it　right？〃　I　change　then　the　suggestion
  of　self…love　into　a　universal　law；　and　state　the　question　thus：　〃How
  would　it　be　if　my　maxim　were　a　universal　law？〃　Then　I　see　at　once　that
  it　could　never　hold　as　a　universal　law　of　nature；　but　would
  necessarily　contradict　itself。　For　supposing　it　to　be　a　universal
  law　that　everyone　when　he　thinks　himself　in　a　difficulty　should　be
  able　to　promise　whatever　he　pleases；　with　the　purpose　of　not　keeping
  his　promise；　the　promise　itself　would　become　impossible；　as　well　as
  the　end　that　one　might　have　in　view　in　it；　since　no　one　would　consider
  that　anything　was　promised　to　him；　but　would　ridicule　all　such
  statements　as　vain　pretences。
  3。　A　third　finds　in　himself　a　talent　which　with　the　help　of　some
  culture　might　make　him　a　useful　man　in　many　respects。　But　he　finds
  himself　in　comfortable　circumstances　and　prefers　to　indulge　in
  pleasure　rather　than　to　take　pains　in　enlarging　and　improving　his
  happy　natural　capacities。　He　asks；　however；　whether　his　maxim　of
  neglect　of　his　natural　gifts；　besides　agreeing　with　his　inclination　to
  indulgence；　agrees　also　with　what　is　called　duty。　He　sees　then　that
  a　system　of　nature　could　indeed　subsist　with　such　a　universal　law
  although　men　（like　the　South　Sea　islanders）　should　let　their　talents
  rest　and　resolve　to　devote　their　lives　merely　to　idleness；
  amusement；　and　propagation　of　their　species…　in　a　word；　to
  enjoyment；　but　he　cannot　possibly　will　that　this　should　be　a　universal
  law　of　nature；　or　be　implanted　in　us　as　such　by　a　natural　instinct。
  For；　as　a　rational　being；　he　necessarily　wills　that　his　faculties　be
  developed；　since　they　serve　him　and　have　been　given　him；　for　all　sorts
  of　possible　purposes。
  4。　A　fourth；　who　is　in　prosperity；　while　he　sees　that　others　have　to
  contend　with　great　wretchedness　and　that　he　could　help　them；　thinks：
  〃What　concern　is　it　of　mine？　Let　everyone　be　as　happy　as　Heaven
  pleases；　or　as　be　can　make　himself；　I　will　take　nothing　from　him　nor
  even　envy　him；　only　I　do　not　wish　to　contribute　anything　to　his
  welfare　or　to　his　assistance　in　distress！〃　Now　no　doubt　if　such　a　mode
  of　thinking　were　a　universal　law；　the　human　race　might　very　well
  subsist　and　doubtless　even　better　than　in　a　state　in　which　everyone
  talks　of　sympathy　and　good…will；　or　even　takes　care　occasionally　to
  put　it　into　practice；　but；　on　the　other　side；　also　cheats　when　he　can；
  betrays　the　rights　of　men；　or　otherwise　violates　them。　But　although　it
  is　possible　that　a　universal　law　of　nature　might　exist　in　accordance
  with　that　maxim；　it　is　impossible　to　will　that　such　a　principle　should
  have　the　universal　validity　of　a　law　of　nature。　For　a　will　which
  resolved　this　would　contradict　itself；　inasmuch　as　many　cases　might
  occur　in　which　one　would　have　need　of　the　love　and　sympathy　of　others；
  and　in　which；　by　such　a　law　of　nature；　sprung　from　his　own　will；　he
  would　deprive　himself　of　all　hope　of　the　aid　he　desires。
  These　are　a　few　of　the　many　actual　duties；　or　at　least　what　we
  regard　as　such；　which　obviously　fall　into　two　classes　on　the　one
  principle　that　we　have　laid　down。　We　must　be　able　to　will　that　a　maxim
  of　our　action　should　be　a　universal　law。　This　is　the　canon　of　the
  moral　appreciation　of　the　action　generally。　Some　actions　are　of　such　a
  character　that　their　maxim　cannot　without　contradiction　be　even
  conceived　as　a　universal　law　of　nature；　far　from　it　being　possible
  that　we　should　will　that　it　should　be　so。　In　others　this　intrinsic
  impossibility　is　not　found；　but　still　it　is　impossible　to　will　that
  their　maxim　should　be　raised　to　the　universality　of　a　law　of　nature；
  since　such　a　will　would　contradict　itself　It　is　easily　seen　that　the
  former　violate　strict　or　rigorous　（inflexible）　duty；　the　latter　only
  laxer　（meritorious）　duty。　Thus　it　has　been　completely　shown　how　all
  duties　depend　as　regards　the　nature　of　the　obligation　（not　the
  object　of　the　action）　on　the　same　principle。
  If　now　we　attend　to　ourselves　on　occasion　of　any　transgression　of
  duty；　we　shall　find　that　we　in　fact　do　not　will　that　our　maxim
  should　be　a　universal　law；　for　that　is　impossible　for　us；　on　the
  contrary；　we　will　that　the　opposite　should　remain　a　universal　law；
  only　we　assume　the　liberty　of　making　an　exception　in　our　own　favour　or
  （just　for　this　time　only）　in　favour　of　our　inclination。　Consequently
  if　we　considered　all　cases　from　one　and　the　same　point　of　view；
  namely；　that　of　reason；　we　should　find　a　contradiction　in　our　own
  will；　namely；　that　a　certain　principle　should　be　objectively　necessary
  as　a　universal　law；　and　yet　subjectively　should　not　be　universal；
  but　admit　of　exceptions。　As　however　we　at　one　moment　regard　our　action
  from　the　point　of　view　of　a　will　wholly　conformed　to　reason；　and
  then　again　look　at　the　same　action　from　the　point　of　view　of　a　will
  affected　by　inclination；　there　is　not　really　any　contradiction；　but　an
  antagonism　of　inclination　to　the　precept　of　reason；　whereby　the
  universality　of　the　principle　is　changed　into　a　mere　generality；　so
  that　the　practical　principle　of　reason　shall　meet　the　maxim　half
  way。　Now；　although　this　cannot　be　justified　in　our　own　impartial
  judgement；　yet　it　proves　that　we　do　really　recognise　the　validity　of
  the　categorical　imperative　and　（with　all　respect　for　it）　only　allow
  ourselves　a　few　exceptions；　which　we　think　unimportant　and　forced　from
  us。
  We　have　thus　established　at　least　this　much；　that　if　duty　is　a
  conception　which　is　to　have　any　import　and　real　legislative
  authority　for　our　actions；　it　can　only　be　expressed　in　categorical　and
  not　at　all　in　hypothetical　imperatives。　We　have　also；　which　is　of
  great　importance；　exhibited　clearly　and　definitely　for　every　practical
  application　the　content　of　the　categorical　imperative；　which　must