 The tendency toward authorial self-reference begun in "Stranger in a Strange Land" and "Time Enough for Love" becomes even more evident in novels such as "The Cat Who Walks Through Walls", whose first-person protagonist is a disabled military veteran who becomes a writer, and finds love with a female character.The 1982 novel "Friday", a more conventional adventure story (borrowing a character and backstory from the earlier short story "Gulf", also containing suggestions of connection to "The Puppet Masters") continued a Heinlein theme of expecting what he saw as the continued disintegration of Earth's society, to the point where the title character is strongly encouraged to seek a new life off-planet.It concludes with a traditional Heinlein note, as in "The Moon Is a Harsh Mistress" or "Time Enough for Love", that freedom is to be found on the frontiers.