Last and First Men
Time travel plays only a tiny role in this classic story of the history of men over the coming two billion years—in that the story itself is transmitted through time into the brain of a 20th century writer.
This book has two authors, one contemporary with its readers, the other an inhabitant of an age which they would call the distant future. The brain that conceives and writes these sentences lives in the time of Einstein. Yet I, the true inspirer of this book, I who have begotten it upon that brain, I who influence that primitive being's conception, inhabit an age which, for Einstein, lies in the very remote future. 
