lightning. Children will laugh at the flashes of lightning, but will
cower before the roaring thunder.

The feeling of fear is closely associated with what is _unknown_. It
is not noise in general that frightens the children, but an
unexpected noise from an unknown source. Indeed, the children like
noise itself well enough to produce it whenever they can by heating
drums, or barrels, or wash-boilers. The frightful thing about thunder
is that the cause remains a mystery, and it is frightful so long as
the cause _does_ remain a mystery, if the child lives to be a hundred
years old. During a thunder-storm children will picture to themselves
a battle going on above. Some think of the sky cracking or the moon
bursting, or conceive of the firmament as a dome of metal over which
balls are being rolled.

[Illustration: Neither are girls afraid to climb.]

The influence of the unknown explains also why that other great
source of fear, namely, darkness, has such a strange hold upon
children. Fear of darkness is very common and often very intense.
There are but few children who do not suffer from it at some time
and to some extent. This fear is frequently suggested by stories of
robbers, ghosts, or other terrors, but even children who have been
carefully guarded sometimes have these violent fears that cannot be
reasoned away.

In order to discover what it is about the darkness that frightens
children, a large number of women and men were asked to recall their
childish experiences with fear, and from the many instances given
the following may be used to illustrate the various terrors of the