 Why was Humphrey being observed?
The pockets of Mr. Humphrey Fownes were being picked outrageously. What made it possible was Humphrey Fownes' abstraction; he was an uncommonly preoccupied individual. But he was thinking about weather, which was an unusual subject to begin with for a person living in a domed city. He was thinking about Optimum Dome Conditions (a crisp 59 degrees, a mildly dessicated 47%) when a bogus postman, who pretended to be reading a postal card, jostled him. In the ensuing contretemps they emptied his rear pants pockets, got his wristwatch and restored the contents of the handkerchief pocket. It all went off very smoothly, like a game of put and take—the sole difference being that Humphrey Fownes had no idea he was playing. It was precipitation peculiar to a dome: feather-light fragments showering harmlessly on the city from time to time. Humphrey Fownes strode through the puffs of falling glass still intrigued by a temperature that was always 59 degrees, by a humidity that was always 47%, by weather that was always Optimum. It was this rather than skill that enabled the police to maintain such a tight surveillance on him, a surveillance that went to the extent of getting his fingerprints off the postman's bag, and which photographed, X-rayed and chemically analyzed the contents of his pockets before returning them. By the time Fownes reached his front door an entire dossier complete with photographs had been prepared and was being read by two men in an orange patrol car parked down the street. Sitting behind the wheel of the orange car, he watched Humphrey Fownes approach with a distinct feeling of admiration, although it was an odd, objective kind of admiration, clinical in nature. It was similar to that of a pathologist observing for the first time a new and particularly virulent strain of pneumococcus under his microscope. Lanfierre's job was to ferret out aberration. Conformity had become more than a social force; it was a physical necessity. He came to see that genuine quirks were rare and, as time went on, due partly to his own small efforts, rarer. Lanfierre was almost proud of Humphrey Fownes. He had even contrived to engage him in conversation once, a pleasantly absurd, irrational little chat that titillated him for weeks. It was only with the greatest reluctance that he finally mentioned Fownes to MacBride. After years of searching for differences Lanfierre had seen how extraordinarily repetitious people were, echoes really, dimly resounding echoes, each believing itself whole and separate. "It's like this, MacBride.
 he didn't act like he was expected to
 he didn't act like he was expected to  to make sure he wasn't a danger to society  he was to be observed before he was allowed to be married  he was suspected of committing crimes