What is the theme in The Caves of Steel by Isaac Asimov?

One major theme is the idea that man is conquerable by the machine. Robots replace men who do a variety of jobs, most commonly manual labor, but also civil services. The notion that the human is no longer necessary to perform everyday tasks begins to tear away at the human soul. Officer Baley struggles with this theme more than anyone, as he is forced to work with a partner who is a robot. This man has spent his entire adult life serving, enforcing laws of justice and righteousness and working towards making New York City a safer place. The idea that a robot is equal or better than him at his own job directly threatens Baley's own existence. Why is he useful anymore if a machine can do his job better than he can? Being dispensable creates lackluster effort and feelings of frustration.