Now  '  substance  '  Descartes  defined  as  that  which  depends  on  nothing  for  its  existence  or  for  its  nature   :sx   that  which  is  independent  in  every  sense    subsistens  per  se .sx   Answering  to  this  definition  there  is  only  one  existent  , the  one  , namely  , that  is  further  characterised  by  the  eternal  and  immutable  possession  of  all  positive  qualities  that  are  ultimately  distinct  , each  in  its  fullest  degree  , i.e.  completely  or  `  perfectly .sx '  And  such  an  existent  is  God .sx   All  that  exists  and  is  other  than  God  depends  for  its  existence  upon  God .sx   Dependence  , however  , is  a  matter  of  degree .sx   Of  those  existents  that  are  the  least  dependent  ( all  matter  and  each  self  ) no  one  depends  on  any  other  , each  is  so  far  independent .sx   Yet  each  does  depend  on  God  and  so  far  is  dependent .sx   Existents  of  which  this  is  true  are  called  `  secondary  substances .sx '  They  are  `  substances  '  in  that  the  existence  of  no  one  entails  that  of  any  other  ;  they  are  `  secondary  '  since  none  is  absolutely  independent  or  unconditionally  existent  , but  , being  dependent  on  God  , each  exemplifies  dependence  at  its  first  remove .sx   Other  existents  again  ( modes  ) are  directly  dependent  on  secondary  substances  for  their  existence  ( formal  reality  ) and  indirectly  dependent  on  God .sx   This  Descartes  sums  up  by  speaking  of  God  as  `uncreated  '  substance  , and  of  all  matter  and  each  self  as  `  created  '  ones  , so  suggesting  an  ultimate  bifurcation  among  the  existents  constituting  the  universe .sx   He  completely  fails  , however  , to  make  intelligible  the  creation  which  results  in  the  dependence  of  created  , finite  , secondary  substances  on  the  infinite  , independent  and  creative  substance  that  is  God .sx   He  appears  to  suppose  that  `  creation  '  is  a  conception  properly  falling  to  theology  for  elucidation .sx   But  it  is  impossible  to  acquiesce  in  such  an  abandonment  of  the  difficulty  , for  the  employment  he  has  made  of  the  conception  is  unquestionably  a  metaphysical  one  , and  is  vital  to  that  view  of  God  and  the  world  which  he  believes  himself  to  have  rationally  demonstrated .sx   This  failure  to  analyse  the  concept  and  to  justify  its  use  , then  , can  be  regarded  only  as  betraying  a  want  of  thoroughness  in  Descartes .sx   It  was  natural  and  useful  , therefore  , that  subsequent  criticism  should  fasten  on  this  very  neglect .sx   The  relation  of  an  uncreated  God  to  the  world  he  has  created  is  far  from  being  clear  and  distinct  , and  it  is  made  no  whit  the  clearer  by  speaking  of  the  continued  existence  of  finite  substances  as  being  virtually  a  new  creation  by  God  from  moment  to  moment    the  regular  recurrence  of  a  miracle .sx   
We  saw  besides  that  Descartes  inconsistently  admits  interaction  between  mind  and  body  in  assuming  uncritically  that  mind  alters  the  direction  ( though  it  does  not  impart  the  quantity  ) of  motion  present  in  physiological  change .sx   Even  though  direction  by  mind  of  motion  already  existing  in  the  body  is  plainly  a  different  thing  from  mind  causing  the  existence  of  motion  there  , both  are  alike  incompatible  with  the  complete  qualitative  disparity  of  mind  and  matter  that  is  essential  to  Cartesianism .sx   
These  are  the  two  principal  defects  lying  at  the  heart  of  the  Cartesian  position  which  are  subjected  to  continual  modification  during  the  second  half  of  the  seventeenth  century  in  France .sx   Superficially  , the  effort  is  to  explain  the  relationship  between  God  and  the  world  , not  by  insisting  merely  on  the  `  necessary  '  character  of  that  relationship  , but  by  exhibiting  in  some  detail  the  several  conditions  under  which  there  can  be  an  effective  commerce  between  its  terms .sx   Formally  , it  is  an  attempt  to  work  out  , with  the  least  deviation  from  Descartes  possible  , a  theory  of  the  universe  which  would  manifest  a  higher  unity  than  that  of  a  collection  , as  well  as  greater  coherence  in  the  determination  of  its  parts .sx   The  critical  and  constructive  effort  of  the  first  period  , to  which  Regis  , De  la  Forge  , Cordemoy  , Geulincx  and  Malebranche  all  lent  their  strength  , was  to  prove  a  failure  too  , though  the  reasons  for  that  failure  are  instructive .sx   A  synthesis  that  is  at  once  more  systematic  and  internally  less  inconsistent  becomes  possible  only  after  the  substance  of  Descartes  has  been  displaced  by  the  Substance  of  Spinoza  and  the  Individual  of  Leibniz .sx   The  extent  to  which  they  withdrew  from  Cartesian  principles  and  introduced  other  and  original  ones  results  in  such  wide  divergences  from  Descartes  and  weakens  so  radically  their  affiliations  with  him  , that  , in  the  end  , Cartesianism  can  hardly  be  regarded  as  being  substantially  constitutive  of  the  new  philosophies  , though  its  formative  influence  in  their  developments  cannot  be  doubted .sx   Thus  it  is  only  in  a  `  historical  '  sense  permissible  to  refer  to  Spinoza  and  Leibniz  as  `  Cartesians .sx '  
I   .sx
One  thing  which  becomes  increasingly  evident  in  the  transition  from  Descartes  to  Malebranche  is  the  inexactitude  of  speaking  of  `  action  '  or  `  causation  '    be  it  of  mind  on  body  , or  body  on  mind  , or  even  of  one  body  on  another .sx   For  the  term  `  action  '  may  designate  with  equal  propriety  two  quite  distinct  things  , viz .sx   ( i  ) the  fact  of  causing  the  occurrence  , hence  the  existence  , of  a  change  or  movement  ;  ( ii  ) the  fact  of  determining  the  character  a  change  shall  assume  , or  the  location  and  direction  of  a  motion  , but  not  causing  its  occurrence  or  existence .sx   To  deny  direct  action  between  mind  and  body  should  mean  in  strictness  a  denial  of  `  action  '  in  both  these  senses .sx   But  Descartes  , we  saw  , denied  it  in  the  former  sense  alone .sx   He  repeatedly  affirmed  action  in  the  second  sense  , and  yet  maintained  there  is  no  interaction .sx   And  according  to  the  view  they  take  on  the  possibility  of  direct  action  between  secondary  substances  , Descartes's  continuators  fall  into  two  groups .sx   There  are  those  , like  Regis  and  Clauberg  , who  follow  him  in  allowing  `  action  '  in  the  second  sense  while  denying  it  in  the  first  ;  and  those  like  Cordemoy  , Geulincx  , and  Malebranche  , who  deny  action  in  both  senses .sx   And  the  question  to  which  these  thinkers  return  their  various  answers  may  be  expressed  in  these  terms   :sx   `  Under  what  conditions  are  secondary  substances  active  or  causative  at  all   ?sx   '   .sx
Before  reviewing  these  several  answers  and  their  grounds  , however  , we  should  notice  briefly  the  views  developed  by  Henry  le  Roy  ( latine  , Regius  ) , who  was  early  an  enthusiastic  admirer  and  a  correspondent  of  Descartes  , and  also  the  first  of  his  followers  to  break  completely  with  his  essential  doctrine .sx   Le  Roy  had  made  extensive  use  of  Cartesian  physiology  in  his  medical  lectures  at  the  University  of  Utrecht .sx   On  the  whole  , the  worth  of  his  zeal  was  perhaps  dubious .sx   His  Fundamenta  Physicae  reduced  the  Cartesian  dualism  of  matter  and  mind  to  a  materialism  , and  contained  so  many  unproved  assertions  that  Descartes  had  openly  to  disclaim  all  responsibility  for  it .sx   Itwould  seem  , however  , notwithstanding  Descartes's  annoyance  , that  Le  Roy  is  right  in  insisting  that  , on  Cartesian  premises  , man  can  be  only  "  a  being  per  accidens  " and  not  a  substance .sx   For  , though  Descartes  had  maintained  the  self's  connexion  with  its  body  to  be  so  intimate  as  to  constitute  them  a  `  substantival  unity,'  he  is  wholly  unable  to  give  this  phrase  a  positive  meaning  that  is  at  once  clear  and  compatible  with  his  definition  of  substance .sx   Whatever  Descartes  may  have  supposed  himself  to  have  established  , or  desired  to  establish  , concerning  the  embodied  self  or  human  being  , the  only  account  of  it  he  is  logically  entitled  to  offer  is    not  that  of  a  substance  of  any  sort    but  that  of  a  unique  kind  of  compound .sx   It  can  be  nothing  other  than  a  compound  consisting  of  a  substance  ( self  ) related  by  some  unspecified  relation  to  a  series  of  material  modes  that  are  collectively  to  be  designated  `  the  body  of  that  self .sx '  Such  a  compound  is  plainly  not  a  Cartesian  substance  , primary  or  secondary  , And  the  breach  opened  by  this  un-Cartesian  view  of  Le  Roy  is  irreparably  widened  by  his  further  declaration  that  mind  is  nothing  but  a  mode  of  corporeal  substance    an  opinion  which  De  la  Mettrie  and  d'Holbach  were  to  develop  more  fully  in  the  next  century  , and  that  connects  him  with  the  current  of  modern  materialism .sx   
Louis  de  la  Forge  , too  , seems  to  depart  from  Descartes's  position  ( though  less  radically  than  Le  Roy  ) in  apparently  maintaining  that  our  voluntary  acts  , but  none  others  , both  cause  the  existence  and  determine  the  character  of  those  actions  of  our  body  that  are  purposive .sx   In  volition  we  not  only  seem  , but  really  are  , both  productive  of  the  ensuing  change  and  directive  of  it  , since  we  determine  it  to  be  of  a  character  suitable  to  achieve  the  end  intended    an  innovation  obviously   .sx
incompatible  with  the  Cartesian  law  that  the  amount  of  motion  in  nature  is  constant .sx   
The  rest  of  Descartes's  immediate  successors  agree  in  not  accepting  this  exception  to  the  attribution  of  all  change  to  God .sx   Regis  reaffirms  Descartes's  view  that  God  alone  causes  or  imparts  motion  , and  allows  the  self  , by  its  volition  , only  the  instrumental  role  of  determining  the  course  physiological  excitations  shall  follow  , and  , thereby  , which  of  our  internal  organs  shall  be  stimulated  into  action .sx   The  experience  we  interpret  as  a  direct  action  of  our  self  on  our  body  is  , therefore  , not  wholly  misinterpreted  , for  some  bodily  actions  are  subsequent  to  , and  determined  by  , our  volitions .sx   Where  we  err  is  in  attributing  more  than  this  to  our  will  , namely  , in  assigning  to  it  efficacy  to  originate  and  impart  a  quantity  of  motion  to  our  body .sx   The  fact  is  , according  to  Regis  , that  divine  and  human  volitions  collaborate  , the  former  initiating  a  physical  change  , the  latter  directing  the  change  initiated .sx   Clauberg  too  agrees  that  the  self  can  do  no  more  than  "  predispose  "  the  body  for  the  changes  ensuing  on  volition  , and  that  the  body  can  exercise  no  action  on  the  self .sx   The  constancy  in  the  apparently  reciprocal  action  between  mind  and  body  is  therefore  referable  to  God's  volition .sx   What  we  now  call  psycho-physical  laws  , and  regard  as  instances  of  transeunt  causation  between  psychical  and  physiological  events  , are  , for  Clauberg  , instances  of  divine  intervention  in  human  affairs  , and  , being  of  a  constant  character  , laws  of  divine  psychology .sx   It  is  in  terms  of  this  conception  that  meaning  must  be  found  for  speaking  of  the  `  union  '  of  self  and  body .sx   The  connexion  cannot  be  one  that  forms  a  compound  substance  , still  less  an  absolute  substance  , but  one  which  merely  co-ordinates  their  actions  and  passions .sx   Further  , Clauberg  thinks  , Descartes's  view  that  persistence  and  succession  in  the  human  individual's  existence  is  the  effect  of  a  continuous  creation  by  God  , calls  for  correction .sx   If  we  have  no  difficulty  in  conceiving  that  our  ideas  cease  to  exist  when  we  no  longer  attend  to  them  , why  , he  asks  , should  we  find  difficulty  in  believing  that  created  beings  would  cease  to  exist  were  God  to  cease  from  creating  them   ?sx   Indeed  , the  analogy  suggested  here  is  , for  Clauberg  , an  over-statement .sx   For  we  are  not  the  masters  of  our  thoughts  , controlling  what  we  shall  apprehend  , as  God  is  the  master  of  His  creations  , determining  what  He  shall  bring  into  existence .sx   
So  far  , then  , we  witness  hesitant  moves  towards  Occasionalism .sx   These  measures  of  De  la  Forge  , Regis  and  Clauberg  , however  , all  leave  untouched  the  original  difficulty  , viz .sx   , if  mind  and  matter  are  wholly  disparate  , how  is  it  possible  for  either  to  determine  the  character  of  a  change  in  the  other  , any  more  than  to  cause  the  occurrence  of  a  change  in  the  other ?sx   Of  this  question  , the  three  thinkers  of  our  second  group    Cordemoy  , Geulincx  and  Malebranche    take  special  account  , and  think  to  answer  it  by  a  doctrine  of  complete  Occasionalism .sx   Cordemoy  points  out  that  the  reason  rightly  given  for  denying  that  will  has  any  efficacy  to  produce  actions  in  bodies  must  also  be  a  reason  for  its  inability  to  direct  , influence  or  determine  the  character  of  any  action  in  a  body .sx   And  in  denying  the  possibility  of  action  in  either  sense  , as  between  not  only  minds  and  bodies  , but  also  one  body  and  another  , he  affirms  the  necessity  of  resorting  to  the  only  other  kind  of  substance  remaining  ( viz .sx   , God  ) for  an  explanation  of  change .sx   Man  is  a  unity  of  a  sort  , but  the  nature  and  behaviour  of  his  body-part  alone  does  not  , any  more  than  that  of  the  self  alone  , enable  us  to  form  a  clear  idea  of  the  union .sx   Mechanics  is  as  powerless  as  psychology  to  explain  it  , for  neither  furnishes  a  concept  which  is  , on  the  one  hand  , neutral  as  between  unified  bodily  mechanisms  and  persistent  selves  , and  , on  the  other  , capable  of  integrating  both  into  a  continuous  unity .sx