Screwtape outlines a fundamental deception:
Men are not angered by mere misfortune but by misfortune conceived as injury. And the sense of injury depends on the feeling that a legitimate claim has been denied. The more claims on life, therefore, that your patient can be induced to make, the more often he will feel injured and, as a result, ill-tempered. Now you will have noticed that nothing throws him into a passion so easily as to find a tract of time which he reckoned on having at his own disposal unexpectedly taken from him. It is the unexpected visitor (when he looked forward to a quiet evening), or the friend’s talkative wife (turning up when he looked forward to a tête-à-tête with the friend), that throw him out of gear. Now he is not yet so uncharitable or slothful that these small demands on his courtesy are in themselves too much for it. They anger him because he regards his time as his own and feels that it is being stolen. You must therefore zealously guard in his mind the curious assumption ‘My time is my own’. Let him have the feeling that he starts each day as the lawful possessor of twenty-four hours. Let him feel as a grievous tax that portion of this property which he has to make over to his employers, and as a generous donation that further portion which he allows to religious duties. But what he must never be permitted to doubt is that the total from which these deductions have been made was, in some mysterious sense, his own personal birthright.
From The Screwtape Letters
Compiled in A Year with C.S. Lewis