The  world  of  consciousness,  for  example,  must  not
be  reduced  in  terms  of  a  set  of  concepts  ultimately
different  from  that  in  which  the  changes  of  the  material
world  are  stated.  Both  are  historical  processes,  and  are
to  be  explained  only  in  terms  of  time-succession  and
under  the  concept  of  uniform  causal  relation.  Human
conduct  must  be  statable  in  the  same  general  terms  as
the  motions  of  things,  the  forms  of  chemical  synthesis,
the  processes  of  life,  if  it  is  to  be  included  within  the
domain  of  science.  Each  element  must  be  conceived  as
part  of  an  orderly  process  the  successive  phases  of  which
arise  in  such  a  way  as  to  make  their  occurrence  predict-
able if  the  full  status  of  their  antecedents  be  given.
That  facts  can  be  treated  thus  is  the  basis  of  all  under-
standing. New  phenomena  cannot  appear  out  of  rela-
tion to  antecedent  events  if  knowledge  is  to  exist.  Sci-
ence is  a  study  of  origins,  and  that  for  which  a  cause
cannot  be  predicated  is  miraculous.  It  lies  outside  the
limits  of  intelligible  existence.  To  be  a  fact  is  to  have
a  cause:  this  is  the  necessary  assumption  of  historical


l66   THE  GENERAL  PROBLEMS  OF  PSYCHOLOGY

science,  and  its  work  is  the  systematic  development  of
the  relations  between  facts  and  their  causal  antecedents.
