Engine Summer is a 1979 post-apocapyptic novel by John Crowley.
Rush that Speaks, the protagonist, is presented as a memory construct, a recording of consciousness taken at a specific time and place. Rush's body lived in an earlier time, and continued on after the recording was made; Rush's recording does not know what happened to him afterwards. The climax of the novel comes when Mongolfier, one of the mysterious "angels" who left Earth after a great war, descends to Rush's body and asks to record his memory for posterity. Rush's recording acts as a personal historical account of life after the war; however, the recording stops when Mongolfier leaves, since Rush's body remains on Earth to live out its life.
The recording acts as a bookend to his quest to find Dr. Boots's List, the mysterious people who live according to another recorded mind; however, he discovers that their recorded mind is that of a cat, allowing them to live with simple, animal instincts and pleasures instead of complicated human desires and emotions. The recording of Rush's mind, in contrast, becomes a tool of the Angels to live vicariously through his life; Rush's recording has been awakened and replayed many times, and will continue to be played in the future, while the Angels take no active role in the colonies of humans on Earth.