The very things that probably made this a lot of fun when it was published (and even when I first read it in early 1990s) now seem to fall flat. Gender norms are reinforced despite the obvious playfullness meant by the 'sex change' of the plot, and for 1970 is might be called progressive, but in a way that's troubling. But what to say? Part of the book hasn't aged well, which is apt for the story – the forward thinking permissiveness of the sexual revolution comes across here as increased sexual availability of women in an ever more expanding patriarchy.

I 'read' this again as an audiobook, and the performer was excellent. His many influential novels include Starship Troopers, Stranger in a Strange Land, The Moon Is a Harsh Mistress, and Time Enough for Love. Long involved in politics, Heinlein was deeply affected by events such as the bombing of Hiroshima and Nagasaki and the Cold War, and his fiction tended to convey strong social and political messages. In 1947, he published a story in The Saturday Evening Post, making him the first science-fiction writer to break into the mainstream market. He started writing to help pay off his mortgage, and his first story was published in Astounding Science-Fiction magazine in 1939. Born in Butler, Missouri, Heinlein graduated from the United States Naval Academy and served as an officer in the navy for five years. He won Science Fiction Writers of America's first Grand Master Award for his lifetime achievement.

He won science fiction's Hugo Award for Best Novel four times, and in addition, three of his novels were given Retrospective Hugos fifty years after publication. Heinlein (1907-1988) is widely acknowledged to be the most important and influential American science fiction author of the twentieth century.

I will fear no evil robert heinlein