The  book  is  not  without  an  a  priori  vein.  The
doctrine  of  mental  and  social  evolution  is  assumed
throughout.  The  world  of  living  men  is  regarded
as  in  process  of  development  from  the  animal  and


Viii  PREFACE

the  primitive  to  the  rational  and  the  spiritual.
There  is  also  a  ^m-assumption,  which  I  think
is  thoroughly  justified,  however,  by  the  evidence,
that  the  typical  religious  revival  is  characterized
by  the  dominance  of  emotion  in  mass  and  in  con
trol.  I  have  been  surprised  at  the  manner  in
which  the  facts  and  principles  of  psychology  have
everywhere  come  to  the  front  as  I  have  worked
on.  I  ought  not  to  have  been  surprised,  for  no
worthy  investigation  in  sociology  ever  was  at
tempted  which  did  not  sink  its  roots  deep  into
the  mental  life.  I  hope  the  book  does  not  lack
insight  into  any  value  which  certain  revivals  of
the  past  have  possessed  for  society,  or  apprecia
tion  of  the  great  human  spirits  who  have  fre
quently  wrought  well  with  what  has  become  a
seriously  defective  religious  method.  I  hope  that
criticism  has  not  exorcised  sympathy.
I  have  undertaken  not  simply  to  discriminate
spurious  and  genuine  revivals,  but  to  show  that
in  genuine  revivals  themselves  there  are  primitive
traits  which  need  elimination  or  modification  in
the  interest  of  religious  and  social  progress.  The
problem  is  not  to  quench  or  diminish  spontaneous
emotion,  but  to  put  it  under  full  rational  control.
