Stability (The Collected Stories of Philip K. Dick, Volume I, Beyond Lies the Wub)

Robert Benton is summoned to a meeting by the Control Office, where he is that a patent application he filed for an invention has been unsuccessful, as the invention could threaten Stability. Benton is surprised, because as far as he was aware he had not filed any such application. Returning home with a set of plans and prototype device given "back" to him by the office, he discovers it to be a time machine.

Activating the device, Benton finds himself transported to an unknown point in history and confronted with what appears to be a living city contained in a glass globe. Despite being warned not to by a mysterious voice claiming to be a "guardian" against evil, Benton feels compelled to take the globe; it then telepathically informs him how to use the machine to return to his own time. Benton does so, but travels to a point in time shortly before he originally left, and deposits his "invention" and the plans at the Control office as a patent application, creating a bootstrap paradox.

After Benton leaves, the Controllers deduce what has happened and go to Benton's home in order to end the threat to Stability. Discovering Benton and the city, one Controller recounts hearing an ancient story of an evil city that had been enclosed in glass for the protection of everyone else. The Controllers attempt to take the globe from Benton, but it breaks, releasing a strange mist, and Benton loses consciousness.

Benton awakes to find himself living in a city where the human inhabitants exist only to service "their Machines". However, neither he nor anyone else has any memory of things being any different; as far as they are aware, life has always been like this.