The End of Eternity - Tapa dura

One of Isaac Asimov’s SF masterpieces, this stand-alone novel is a monument of the flowering of SF in the twentieth century. It is widely regarded as Asimov’s single best SF novel.

Andrew Harlan is an Eternal, a member of the elite of the future. One of the few who live in Eternity, a location outside of place and time, Harlan’s job is to create carefully controlled and enacted Reality Changes. These Changes are small, exactingly calculated shifts in the course of history, made for the benefit of humankind. Though each Change has been made for the greater good, there are also always costs.

Isaac Asimov lived in Boston and in New York City for most of his life. He died in 1992 at the age of 72.