The theme of "Paul's Case" is that when the world of illusion, of the superficial, becomes too appealing to us, it can destroy us.
We can feel some sympathy for Paul as he rejects the narrow, hard-working, respectable, and Calvinist world he has grown up in. He wants more than a drab life working in an office and sitting on a Pittsburgh stoop in the evenings. He longs for beauty, but his longing is entirely shallow. We are told that:
It would be difficult to put it strongly enough how convincingly the stage entrance of that theatre was for Paul the actual portal of Romance.
In other words, Paul can't distinguish between surface illusion and reality.
Paul becomes so desperate for a more colorful, beautiful life that he steals a thousand dollars from the bank where he works, quite an amount of money at the time, and heads to live the high life in New York City. This life completely appeals to him. The story says he feels no remorse:
The flowers, the white linen, the many-colored wine glasses,...
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