Whenever there's a book I should be reading, no matter how much I might enjoy that book, I'll usually pick up something else. There's a book I should be reading right now, so I picked this collection of David Brin stories that I'd already read off the shelf. Except, it turns out I hadn't read them before, just the first story, so whenever I had previously picked it up off the shelf, I'd look at the first story and go, "oh, I guess I've read these before," and put it back. (I have a terrible memory for short story collections. In runs in the family -- my mother can read Agatha Christie books over and over because she forgets who did it.)
Anyway, River of Time is a collection of some of David Brin's earlier short stories. There's a few clever ideas here, but I find his novels a lot meatier.