(1) Like    marble  to  receive and like    marble  to  retain.
(2) Like    wax to  receive and like    wax to  retain.
(3) Like    marble  to  receive and like    wax to  retain.
(4) Like    wax to  receive and like    marble  to  retain.
The first   type    gives   us  those   who memorize    slowly  and with    much    heroic  effort,
but who keep    well    what    they    have    committed.  The second  type    represents  the
ones    who learn   in  a   flash,  who can cram    up  a   lesson  in  a   few minutes,    but who
forget  as  easily  and as  quickly as  they    learn.  The third   type    characterizes   the
unfortunates    who must    labor   hard    and long    for what    they    memorize,   only    to  see
it   quickly     slipping    from    their   grasp.  The     fourth  type    is  a   rare    boon    to  its
possessor,   enabling    him     easily  to  stock   his     memory  with    valuable    material,
which   is  readily available   to  him upon    demand.
The particular  type    of  brain   we  possess is  given   us  through heredity,   and we  can
do  little  or  nothing to  change  the type.   Whatever    our type    of  brain,  however,    we
can do  much    to  improve our memory  by  obeying the laws    upon    which   all good
memory  depends.
2. THE FOUR FACTORS INVOLVED IN MEMORY
Nothing is  more    obvious than    that    memory  cannot  return  to  us  what    has never
been    given   into    its keeping,    what    has not been    retained,   or  what    for any reason
cannot   be  recalled.   Further,    if  the     facts   given   back    by  memory  are     not
recognized  as  belonging   to  our past,   memory  would   be  incomplete. Memory,
therefore,  involves    the following   four    factors:    (1) registration,   (2) retention,  (3)
recall, (4) recognition.
Registration.—By     registration    we  mean    the     learning    or  committing  of  the
matter   to  be  remembered.     On  the     brain   side    this    involves    producing   in  the
appropriate neurones    the activities  which,  when    repeated    again   later,  cause   the
fact    to  be  recalled.   It  is  this    process that    constitutes what    we  call    "impressing the
facts   upon    the brain."
Nothing is  more    fatal   to  good    memory  than    partial or  faulty  registration.   A   thing
but half    learned is  sure    to  be  forgotten.  We  often   stop    in  the mastery of  a   lesson
just    short   of  the full    impression  needed  for permanent   retention   and sure    recall.
We  sometimes   say to  our teachers,   "I  cannot  remember,"  when,   as  a   matter  of
fact,   we  have    never   learned the thing   we  seek    to  recall.
