The book is divided into three main sections. The middle section contains a story about life forms in a parallel universe. This section made the book memorable and worthwhile. The life forms were interesting and unique. I even found myself getting emotionally attached to the little fellows. The ending of the section was satisfying and surprising.
Some of the discussion in the book is timeless. A major part of the plot deals with the safety of the energy technology. If I hadn’t known that the book was written in the early 70’s, I would have thought it was inspired by the politics of Climate Change and Global Warming:
"It is a mistake,” he said, “to suppose that the public wants the environment protected or their lives saved and that they will be grateful to any idealist who will fight for such ends. What the public wants is their own individual comfort."Asimov also offers wisdom on how to counteract some of those arguments. I think the Hugo voters got this one right.