I had to reread this after just watching Predestination on which it was based. I was impressed with the movie but even more so with the story. I guess I picked up more nuances this time. It was all the more impressive because of how the character study really played out and what wasn't said but could be deduced. I think I can thank the movie more for that aspect, although one storyline hadn't existed in the short story. 
 Even so, very impressive ideas and a minimalist style that was so understated that I'm not too surprised I missed it the first time. Preferred some of his other short stories more, but maybe I need to revisit them all and see how my grown up self takes them. 
 What can I say? It was tight and impactive and so very easy to see how it informed the later third of his novels in both strangeness and, dare I say it, incestuousness? Absolutely, but I'm of a mind that Heinlein is still the Grandmaster and should retain the title forever, regardless of the kinds of stunts he has been known to play. After all, he's not merely informative and didactic. He's one hell of a storyteller.