Time Enough for Love

Warning: Plot details follow.

The book is about Lazarus Long, the universe's oldest living person, who is tired of living and wants to die.

The book takes the form of several Novellas tied together in the form of Lazarus's retrospective narrative.

One of the stories is about a US naval cadet who was "too lazy to fail." A lengthy, western-style story about his days as a pioneer surprises us, being rather un-SF fare for a book proclaimed as a SF classic. (On the other hand, the pioneering does take place on another planet, and several genetically engineered animals -- notably some talking mules -- accompany Lazarus on his venture.) There are two "intermissions", taking the form of lists of provocative phrases and aphorisms, each some six or eight pages long. Possibly based on the authors views on life, universe and everything, some of these have became quite popular and can be found (amongst other things) in internet signatures to this day. Another story is the high-tech colonization of a planet in the "modern" way. There is a bit of time travel at the end.

This book gets tied in with The Number of the Beast also by Robert A. Heinlein, and through it is tied to The Cat Who Walks Through Walls and several other Heinlein novels.