Everything which you wish to remember does not take form in a definite
object which can be visualized and often presents a more difficult
problem. Fortunately the mind only requires a hint or suggestion to
start the Law of Association into operation which will bring the
thought not in itself easily pictured. As the child progresses his
imagination will find many original ways in which to create Reminder
Pictures to aid him in remembering abstract ideas. This ability will
not come except by practice and effort; if he is allowed to consider
the remembering of abstract ideas an obstacle to success it will be so;
but if he tries to master these he will find it is not difficult to
create a picture which will remind him of what he wishes to remember.