NERVOUS  CONSERVATION  AND  MENTAL  WORK    305

or  during  ordinary  sleep,  tend  to  work  themselves  out
in  the  waking  period;  and  sometimes  our  most  brilliant
thoughts  come  apparently  of  themselves.  Somewhat  as
breathing  and  the  other  vital  processes  go  on  without
conscious  direction,  our  thought  currents,  after  being
started,  tend  to  evolve  themselves  automatically.  The
brain  worker  is  naturally  concerned  in  the  proper  direction
and  use  of  his  subconscious  processes.
How  to  Use  the  Subconscious.  —  Although  the  nature
of  the  subconscious  brain  processes  is  not  understood,  the
matter  of  utilizing  them  in  mind  work  appears  not  to  offer
serious  difficulty.  For  example,  a  minister,  in  speaking
of  his  method  of  preparing  sermons,  said:  "We  ministers
have  a  way  of  selecting  a  theme  many  days  before  the  work
of  writing  the  sermon  is  begun.  This  theme  with  its
related  facts  is  kept  constantly  in  mind  —  to  be  brooded
over  as  it  were.  When  the  time  for  writing  comes,  it  is
found  that  the  sermon  has  assumed  its  essential  propor-
tions and  needs  only  to  be  put  into  the  required  literary
form."  The  conditions  observed  by  the  minister  and
by  all  successful  brain  workers  are  four  in  number:  i.
Interest  in  the  subject  which  may  be  either  natural  or
acquired.  2.  A  sufficient  stock  of  material  upon  wrhich
the  mind  is  to  work.  3.  The  habit  of  concentration  re-
ferred to  above.  4.  Persistent  effort  along  the  chosen
line  of  work.
