This is a perfect bus book -- most of the stories are short and self-contained, but eventually, they all fit into a weird sort of web that Heinlein's been weaving since way before I was reading. The fit isn't always seamless, but it's plenty good enough in this time of news "briefs" and 2GHz Pentiums. This collection chronicles Man's first creeping into space and, almost as an afterthought, the development of the Howard family, a group of people who, due to clever selective breeding, tend to live much longer than their contemporaries. Bully for them!