The capstone and crowning achievement of Heinlein’s famous Future History, TIME ENOUGH FOR LOVE follows Lazarus Long through a vast and magnificent timescape of centuries and worlds.Heinlein’s longest and most ambitious work, it is the story of a man so in love with Life that he refused to stop living it; and so in love with Time that he became his own ancestor.
(From the books back cover)
I think Heimlein is one of my favorite authors. “Time enough for Love” was nominated for the Nebula Award for Best Novel (1973) and the Hugo and Locus Awards (1974) and although did not finally win, nonetheless it is quite an interesting read.
As always, I cannot outdo the Wikipedia article about the book.