Dedication: to the librarians.

During the 1930s and 1940s anyone writing science fiction did so almost exclusively for magazines. Then in the early 1950s the magazine market began to die and paperback books took over. But the paperback were on the stand one week and gone the next. By the time an author's newest book came out his older books had disappeared.

As a result, during these later years, when the magazines were mostly gone and the paperback books were coming and going, there were only a few of us who could afford to be full-time writers of science fiction; and the fact this was possible at all was only because libraries continued to be the only real market for hardcover science fiction. The libraries alone bought science fiction books on a regular basis, archived them, and made them continuously available to readers; and in this way libraries kept both science fiction and those of us who wrote it, alive.

To libararians everywhere, therefore, this book -- the youngest of my literary children to see the light of day -- is dedicated.