how the
mind experiences a more or less unconscious _(d) preparation for the
ensuing scene_.

Suppose you have a comedy scene showing a bathtub gradually filling
with water because the faucet was left open. In the time required to
fill the bath and cause it to overflow, five or six hundred feet of
film would be used up if the scene were not changed. Instead of this
waste of film, you could, after registering the fact that the running
water was rapidly filling the bath, introduce a leader: "Ten minutes
later--the tide rises."

Such a leader prepares the spectator for the funny scene that is to
follow; and when the next scene is shown, in which the water is
overflowing the bath and turning the bathroom into a miniature lake,
the spectator realizes what has happened in the ten minutes which,
according to your leader, has elapsed since the last scene was shown.

Or, in your story, a lumberman may be injured by having a tree that he
is chopping down fall on him. To show the whole process of felling a
good-sized tree would take too long--it would consume too much
footage, and be monotonous to the spectator. Also, it is the effect
and not how it is obtained that makes a picture of this kind
successful. For these reasons the man should be shown as he starts to
chop down the tree. Then after he has made some perceptible progress
you might introduce a leader. "The accident;" and, following the
leader, show the man pinned to the ground by the fallen tree; then
proceed with the succeeding action. You may be sure that the audience
will understand that the man has been knocked down by and pinned under
the tree as it fell; it is only necessary to show these two scenes.

A leader, however, should never be employed to "break" a scene unless
there is absolutely no chance to introduce in its stead a short
_scene_, the showing of which will help the progress of the plot; or
unless a leader will serve the double purpose of breaking the scene
and supplying the audience with an explanation that is important just
at that time.

Taking the two examples just given, in which a leader is used to break
the scene, there is scarcely any doubt that, were you writing these
scenes in scenario form, you might easily substitute scenes that would
help the action of the story and allow you to dispense with the
leaders altogether. For instance, you could show the scene in which
the absent-minded man leaves the water running into the bath and goes
out