I guess my thirty-first entry is a good time to return to the author of my first bookshelf entry. This will not be the last entry for Robert Heinlein.
This 1958 book is an enigma. It has so many holes in the plot that it resembles Swiss cheese, getting more and more outlandish as it progresses, straining any reasonable suspension of disbelief well past breaking point, at the same time challenging the reader with rigorous maths and science, yet it is so engaging that when I re-read it recently I couldn't put it down and finished it in the same day. I guess that it has, with less polish, all the elements that made Heinlein a science fiction rock star.
This quote from the book illustrates what a perceptive person Heinlein was and why we must treasure his works.
"...library science is the foundation of all sciences just as math is the key - and that we will survive or founder, depending on how well the librarians do their jobs."