Roughly, the action of a character should be unpredictable before it has been shown, inevitable when it has been shown. In the first half of a novel, the unpredictability should be the more striking. In the second half, the inevitability should be the more striking.

children like change - for one thing, they never anticipate regret.

Story involves action. Action towards an end not to be foreseen (by the reader) but also towards an end which, having been reached, must be seen to have been from the start inevitable.

All good dialogue perhaps deals with something unprecedented.

If a theme or idea is too near the surface, the novel becomes simply a tract illustrating an idea.

Everything is very quiet, the streets are never crowded, and the people one dislikes are out of town.

The story must spring from an impression or perception pressing enough to have made the writer write. It should magnetize the imagination and give pleasure.