I discovered Robert A. Heinlein back in sixth grade. It was 1969 (which makes me old, I guess). Luckily for me, the book I found was Rocketship Galileo, which – coincidentally – was Heinlein’s first published novel. That book, as well as most of the author’s, are dated these days, but I still pick them up and read them with that same sense of wonder that sent an 11-year -old reader looking for a bigger world than the Hardy Boys, Nancy Drew, and even Tom Swift, Jr. offered.

Rocketship Galileo offered machine-gun toting Nazis on the moon. That threat had still loomed in the world when Heinlein authored the book, and it wasn’t too far gone from what I remembered.

I went on to enjoy Citizen of the Galaxy, Starship Troopers (made into a movie with computer programming that Heinlein would perhaps have never conceived), Between Planets, Red Planet, and a couple dozen others. I was in heaven. Heinlein was writing the world I thought I’d be living in by now.

Lately I came across a Heinlein book I hadn’t read: The Door Into Summer. I settled in for a treat, a return to a boyhood I remember fondly. In the book, Dan Davis is an engineer in the futuristic world of 1970 (Heinlein actually wrote this novel in 1957, so he was writing near-future fiction).

After designing a whole line-up of automatons that clean up around the house, Dan goes into business with a friend and establishes a company called Hired Girl. His next big project is Flexible Frank, an automaton that can do all the things humans do.

Unfortunately, Dan and his business partner have a falling-out over a conniving woman named Belle who manages to take lock, stock and barrel everything that's not tied down. After an angry confrontation, Dan is injected with a zombie drug and taken down to be put into Cold Sleep, a cryogenic chamber and awakens 30 years later in the year of 2000.

Dan finds he loves the world of the future but misses his friends, in particular his cat, Pete, and almost-niece Frederika. The future holds marvels Dan has never dreamed of, but it also holds a really strange past for him, one that he doesn't remember and feels certain he never lived through — until he finds out that time travel exists.